Research and Development 2019-2020
Design and Build of
Prototypes for
TWP’s Fractal Aluminum Structure and
Energy-Storing,
Photovoltaic, Piezoelectric, Pyroelectric and Electroluminescent Cell.
The following text is a treatise and account
of 12 months practical and experimental research and development, in
the form of a science and history lesson; it explains and outlines the
principles behind
the drive to produce TWP, a cost-efficient system and apparatus
intended for mass-production and widespread adoption.
Albert Einstein said, “If you
can't explain it to a six year old, you don't understand it yourself.”
Even so, many technological enterprises are so complex, that
nobody is qualified enough to comprehend it. This phenomenon is
exploited of course, a story as old as the Emperor’s New Clothes, in
which the tailor was paid handsomely. So let’s swallow this pill :) We
will try to add a spoonful of sugar to make
the medicine go down. Like a tree, there will be some tangents; also
like a tree, we will eventually arrive at a point.
My six-year-old, experimenting with Newtonian physics, Venice Beach
Quantum Mechanics
Beginning with a light
subject.. pun not intended. This joke might make more sense by the end
of this section, but since you haven’t got there yet, I will say that
light is made of photons and photons are quantum particles, as are electrons.
Photons are light, and electrons are ‘electricity,’ and since
one of the functions of our apparatus is to generate electric
electrical energy
from light, the basic principles of this mechanism should be understood.
The word ‘Quantum’
is
ubiquitous now in society. It represents the frontier of human
understanding, yet we see it used for marketing, techno-bamboozling,
even self-help books, and no normal person is expected to understand
it. We are not encouraged to understand it, and the language used to
describe it is as secretive as the Latin that was once used by doctors
to write their prescriptions. Like religion, the new priesthood are the
ones reading the scriptures; they are the purveyors of ‘truth.’ With quantum physics,
the truth is kept not by priests but by people in lab
coats, or professors in university classrooms. Our daily lives have
been shaped and influenced by some of these chalk-wielding brainboxes
that have explored the mysteries of the same phenomena we are all
experience every day and may take for granted; matter, energy, and the
patterns of nature.
You might ask if quantum
physics is relevant to solar R&D. Quora has answered this question:
Q: “How
useful is quantum
mechanics in solar energy”
A: “For a theoretical understanding of how photovoltaics work, having
some understanding of quantum mechanics is absolutely central to
getting anything done, such as computing the theoretical efficiency of
a given cell for a given light spectrum. It’s a 100% quantum effect.”
By the end of this section,
you will understand what quantum physics is (which may not be quite the
same
as ‘understanding quantum physics’); why it is called quantum physics,
and what makes it different to regular physics. There will be no math
and there won’t be a test at the end of this. It’s a complex subject as
evidenced by Richard Feynman’s description - “There was a time
when the
newspapers said that only twelve men understood the theory of
relativity. ... On the other hand, I think I can safely say that nobody
understands quantum mechanics.” Feynman was a professor at Caltech here
in Pasadena, and won the Nobel prize for his contributions to Quantum
Electrodynamics (the interaction of light and matter).
Interesting loosely related
fact: It can take a photon millions of years and longer to reach us
from across the galaxy. The light we see may have been emitted before
the dinosaurs existed. However, since time passes more quickly the
faster we travel, and a photon travels the speed of light, a journey
that seems like millions of years for us, seems like only a moment to
the photon. In that sense, photons do not experience time. That’s
relativity.
Dictionary definition of
quantum: a discrete quantity of energy or any physical quantity.
Dictionary definition of
discrete: individually separate or distinct.
So, ‘quantum’ as a word can
be described as a fixed irreducible single unit of something. It can’t
become smaller than it is, and it can only get larger by adding
multiples of itself. Like Lego. It’s an absolutely fixed unit.
Atoms
are made up of protons, electrons
and also neutrons.
If an atom was the size of a
cathedral, the particles wouldn’t even be the size of flies, yes these
particles move so vigorously that they would have the properties of a
cathedral in terms of ‘volume’ - not because the particles are solid,
but because they generate magnetic fields, the same magnetic fields we
are familiar with in iron magnets, only the distance is different.
Electrons are considered
elementary particles; they are indivisible, and nobody truly knows what
they are. Protons and Neutrons on the other hand, can be further
subdivided (by smashing them using particle accelerators) into quarks; nobody know what they are either. Electrons whiz, vibrate, or
‘appear’ (in two places at the same
time, like photons), around the nucleus of an atom, (at approximately
1% the speed of light in a hydrogen atom, but are capable of moving at almost
the speed of light) while the electron itself is also spinning.
Einstein published a paper describing electrons as singularities,
or in other words, ‘little black holes’ whereby electrons and black
holes could be described in the same way, mathematically. There are
many that reject this premise, but their reasoning is as unsatisfying
as the premise itself is inspiring.
Hydrogen
is the simplest atom;
it is the lightest element, and the first element in the universe to be
formed before all the heavier elements were fused
from hydrogen in the
furnaces of stars. A hydrogen atom consists only of a single proton and
a single electron. The electron in this atom is the same as all
electrons everywhere - they're all identical. If you remove the proton
from this same hydrogen atom, it will be the same as any other proton
in any other atom. All electrons and protons are the same. All the
elements heavier than hydrogen on the periodic table were made with the
building blocks of hydrogen electrons and protons.
Newton gave us the rules of
physics that are accurate enough to get to the
moon, launch satellites,
and space probes. It seems like everything we can see and touch adheres
to these rules so faithfully that they would seem like the be-all and
end-all of physics. Except it has its limits, and not just when it
comes to ‘non-newtonian’ fluids. Without a little help from
Einstein’s
relativity, GPS satellites would be out of synchronization, as their
velocity actually means they experience time at a different rate to the
ground.
We
are used to various
rules which seem to be incontrovertible in the physics we deal with
every day - gravity; momentum; friction; thermodynamics; acceleration;
volume; mass; density; temperature; pressure and many other constants.
They are reliable too. Hold your hand out, release an apple, and
it will fall down to the ground. It will not float into space. Now do
it a thousand times and see how reliably it does this every time. Heat
water to make a coffee, and it always boils. Every time. No two
‘objects’ are ever the same; snowflakes, fingerprints, DNA, even twins;
they’re always slightly different, whereas quantum particles of the
same type are identical.
The rules change for the molecules,
the atoms, the electrons,
protons and neutrons. Everything else above these particles in scale is
divisible but these particles are not (yes, protons and neutrons can be
divided into quarks but they would cease to be protons and neutrons).
Photons are also indivisible and identical to one another (although
their energy level and wavelength can change,
which correspond to
both amplitutude and where they fall on the electromagnetic spectrum). Photons and electrons
interact; photons can excite electrons to a higher ‘orbit’ which is the
principle driving photovoltaic applications and excited electrons
can emit photons, which the principle driving electroluminescent applications. It works
backwards too; high-energy gamma radiation (photons) can be used to make
electrons, though we will not be doing that experiment.
On a fundamental and pragmatic level, matter and energy are
interchangeable. You might even think of matter as ‘captured light’ or
as Yoda said, “Luminous
beings are we. Not this crude matter.”
These indivisible quantum
particles are not governed by the
classic laws of physics: gravity; momentum; friction; thermodynamics;
acceleration; volume; mass; density; temperature; or pressure; they are
not even 100% reliable; sometimes the proverbial
pot
boils, sometimes it doesn't. When you shine photons though glass, a
certain amount of these photons will go through the glass, and some
will be reflected back. Do we know which photons will pass through and
which will be reflected? No - we must use probability to predict the
behavior of large numbers of these particles. Unlike releasing an
object with our hand, and watching it fall to Earth, which we expect to
occur 100% of the time, with quantum mechanics there is uncertainty. All
the rules of classic physics do not apply, there is an entirely
different set of rules which must be learned. These rules can be pretty
crazy
and unintuitive; as Richard Feynman said, “Nothing you’ve experienced
can prepare you for this.” The kookiest
quantum behaviors
and theories boggle the mind. Electrons can even become entangled when you bring them close together, and then when you separate them by any distance, like psychic twins, the one shares the other’s feelings; excite one electron, and the other gets excited at the exact same time, and the signal between the electrons travels faster than the speed of light; it’s instantaneous. This is quantum entanglement.
Prepared
active ingredients for cell prototype
Quantum Chemistry
Linus
Pauling was a
professor at Caltech, in Pasadena, 1927–1963. He was a
top-drawer
smarty-pants; ranked as the 16th most important scientist in history,
author of “chemistry's most influential book of this century and its
effective bible,” The Nature of the Chemical Bond; and the only person
ever to win two unshared Nobel prizes. Pauling pioneered and co-founded
the field of quantum chemistry, which is the quantum mechanics
of
chemical reactions. Angela
Merkel, PM of Germany, has a PhD in quantum
chemistry. On a related side-note, Merkel has shut down several of
Germany’s
oldest nuclear power plants offline, and plans to permanently close all
of them by 2022, with complete dependence on renewables. Her
qualifications make these actions all the more interesting.
We established that
electrons are in all
matter, and that electromagnetic radiation (light, infrared,
ultraviolet, radio,
x-rays etc) is made of photons. You could say that photons and
electrons are the most mobile and active of these quantum particles.
Photons whiz around through vacuums and matter at the speed of light
(and experience no time) and in our world, electrons usually orbit an oppositely charge nucleus, though with some encouragement they will travel along a copper
wire, though actually quite
slowly (as slow as 1mm/second)
however the signal is transmitted at practically the speed of light
(much like a quantum Pez dispenser) or faster even. The fact that the electrons travel
so slowly (along a wire) but provide so much energy shows you just much power is ‘in’
them.
Electrons are negative in
charge, and protons are positively charged, so it would be intuitive to
think they are counterparts, but they are not. Protons have far less
mobility than electrons, and in fact, electrons already have an equal
and opposite counterpart - the electron
hole. It is what is sounds
like, it is the absence of an electron, but somewhat confusingly, this
counts as a ‘positively charged particle’ or ‘quasiparticle’ and is the
meaning of the
plus-sign on any battery you might see. The negative symbol is for the
electrons.
Electrons
are the driving
force in all chemical reactions, bonds and physical properties.
Electron states dictate colors, flavors, friction, magnetism, even
water surface tension. Besides the obvious electronics,
motors, and
communications devices; adhesive tape, soap, cooking, organic
life-cycles,
everything that involves the properties or behaviors of matter.
According to wikipedia, oxidation (whether it is an apple cut open, or
iron rusting) is described simply as, ‘the loss of electrons.’ Vitamin
C is an antioxidant, and it does this by donating
electrons.
Electricity is essentially the movement of electrons; therefore vitamin
C is
electricity; you can taste the electrons, mmm. Interesting fact, Linus
Pauling encouraged Richard Feynman to consume vitamin C for his health
later in life. Pauling was a well-known advocate of vitamin C, an
obsession that might have been hard to understand otherwise without
knowing the quantum mechanics behind it all. An interesting side note
to further demonstrate that electrons play a part in everything
including biology; the blue dye ‘Methylene
blue’ is used as an
“alternative electron acceptor” to treat methemoglobinemia
and other more exotic conditions. Prussian
blue dye is used to treat
thallium and cesium
poisoning (both radioactive), although it’s not entirely clear whether
either works as an
electron receiver or donator. Literature tends to play it safe and
suggest that it “plays a part in the transfer of electrons.” Since the first atomic explosions in 1945, every living thing on the planet contains cesium
137; the
next
time you see someone chugging a blue gatorade or necking blue M&Ms,
they might not seem as crazy. The fact
that substances’ color can be indicative of their electron state and
therefore function, is notable, but not constant; zinc oxide and white
lead are both white, but
one of them is a food additive and the other is poison.
Linus Pauling created the
periodic table of electronegativity
which is still used today. All the
elements on the periodic table have varying abilities, or tendencies to
either donate or receive electrons. This phenomenon is utilized in diodes.
Diodes are more interesting than they sound; lasers are diodes, solar panels are diodes, televisions are diodes,
light emitting diodes
are diodes. It might be worth knowing what a diode is. The most common
type of diode is a semiconductor
that creates a bias for the flow of electrons in a particular
direction. This semiconductor is most often made of a single ceramic,
but which
has been doped with different impurities on each end, or side, of the
diode. One half, or part, is doped to be biased towards
electron-donation (n-type), the
other is doped for electron-receiving (p-type). A silicon
solar panel is made of two flat surfaces of silicon, the upper half and
the lower half being doped with different impurities. When photons
excite the free electrons that exist between the boundary between these
two differently doped semiconductors, they are compelled to travel
along the electron gradient created by the imbalance at the interface
between the two
semiconductors.
Devices that utilize the programmability
of materials by combining semiconductors of varying
properties, including electronegativity, are able to perform various
and
countless functions without any moving parts - they are solid-state. A
simple example of a solid-state would be a security light with a motion
sensor; a more complex example would be a modern television (unless you
count buttons), a touchscreen smartphone, or a solar panel. Most
technology seems to evolve towards the solid-state version of itself,
since the introduction of the transistor.
A transistor is a
semiconductor which acts as a switch, with no moving parts. This
allowed for the miniaturization of electronics and the microchip
revolution. Computers have always essentially been machines with
countless switches, either switched on or off, 1 or 0. With enough
switches, highly complex functions can be performed. The switches are
more clearly visibly in the first computer, Charles
Babbage’s Analytical Engine. An interesting side-note; Ada
Lovelace, the daughter of poet
Lord Byron, was the first person to write an algorithm
for
Babbage’s machine, which makes her the first ever computer programmer.
In the transistor, those
same ‘switches’ did not require moving parts; they could switch on and
off
very, very quickly; be vastly more numerous, and extremely tiny.
Vinyl-cut stencil for
electron-collecting electrode
Tiny Distances and Surface States
Since electrons are
responsible for the bonds between atoms and molecules, most of the
electrons in an ‘object’ are occupied and unavailable, holding onto
other atoms. If there are a surplus of electrons, or electron holes, we
can say that the material is ‘charged.’ An atom or molecule with a net
negative or positive charge is called an ion.
Anions are negatively
charged, cations are positive.
In a negatively or
positively charged object, these surplus electrons or electron holes, gather
on the outside of the object. There, they are available, to
either migrate to another object, or travel through, or more
accurately, across, its own surface. When electricity travels ‘through’
a metal wire, the electrons are actually traveling on the surface of
the wire, between the metal and the insulation (if there is one).
It is possible to make a
material
which is mostly only ‘exterior’ surface area, and not much else, such
as a
single molecule layer of graphene.
These single-molecule-thick
materials are often called 2-dimensional materials and are readily
available. When graphene is a single molecule thick, it becomes an
unparalleled superconductor. In this quantum world, tinier can
be
better; much like an Edison lightbulb glows brighter when the filament
is thinner. In a silicon solar cell, all the electrons are being
excited at the interface
between the differently doped semiconductors,
and not inside the materials themselves; it could be inconceivably thin
and it would still function as well, as long as the interface
between
the two materials was the same. The only functional part of the solar
panel is actually, literally, 2-dimensional, and even a moderately thin
solar panel, is either mostly wasted, or support material so the cell
doesn’t collapse under its own weight.
Electrons are very, very
small things. By their nature they are smaller than atoms, because
atoms are made of electrons and not the other way around, and atoms are
still very small things themselves. We know that an object’s ‘surplus’
and ‘available’ electrons hang out on the surface, where they seek
balance by being attracted to oppositely ‘charged’ materials and being
repelled by similarly charged ones. We can demonstrate this practically
by rubbing a balloon on our heads; or placing a comb
next to lightly
flowing water, to see this magnetic effect at a distance. Water is
positively charged, and is attracted to the electrons (which are
negative in charge) that collect on the increased surface area of the
comb. You can also observe where there is no attraction between
materials, like water rolling off teflon. Both are positively charged,
and do not attract, they repel. This allows increased surface tension
of the water,
which is the point in scale where the behavior of water can be
observed as being more strongly affected by quantum effects than by
Newton’s laws of physics. This is also the case with capillary action
which is caused by adhesion, and adhesion is a result of the quantum
effects of electron interactions. Interestingly, adhesion, officially
at least, remains a mystery. That’s right, nobody really know why
things stick to each other. The best we have are ‘theories of
adhesion’; no less than five different forces are considered to be
significant but so far there is no consensus as to how much of the
consequence is due to which force. It’s good to remember that we don’t
and can’t know everything; far from being limiting, this reminds us
that there is potential for improvement in almost all things.
These
tiny electrons can be
stored, or gathered for later use, but you can’t put them in your
pocket and not in a plastic bag, and you can’t hold them in your hand.
Well you can, but all the electrons on your hand are otherwise
occupied. Storing electrons (and electron holes) is only useful if you
are able to retrieve them for later use, when you want to charge your
phone or switch on your flashlight (forgetting for a moment that
batteries exist and that they are an abstract concept that doesn’t help
us understand how electrons are stored). Since electrons are so tiny,
they need tiny spaces to store them. They can actually be stored using
an empty space, or gap, between two conducting surfaces; the electrons
aren't stored in the gap; the electrons and electrons holes gather in
‘numbers’ on either side of this gap, or empty space, but they never
touch. This gap needs to be very small, because electrons are small,
and they must be close to each other to be able for their forces to
interact (without touching). It is these gathered electrons and
electrons holes which can be recalled for later use.
When there is an increase
in numbers of electrons and holes on both sides of the gap between the
conducting contacts, we are building up a ‘charge’
ie. charging the
battery, or charging a capacitor. Often, a ‘spacer’ is used to
maintain, or enhance the effect of, this gap, especially by using a dielectric
material instead of simply air, paper, plastic, glass or ceramic.
This is the concept of a capacitor.
If you look at the symbol for capacitors, it looks like a
gap between two plates. A capacitor stores electrical charge for later
use, in innumerable devices we use every day. Capacitors are
recognizable as one of the more important and mass-produced components
in electronic circuitry, but the story of the capacitor is also the
story of the battery too.
The first ever electrical
battery capable of producing a continuous current was made by Italian
physicist Alessandro Volta in 1799; his
battery consisted of many
alternating zinc and metal discs stacked on top of each other with tiny
gaps between them, using brine-soaked cardboard or felt spacers to
maintain the gap distance.
The first use of the term
battery is credited to Benjamin
Franklin in 1748, as published in an 1767 account titled, “History
and Present Status
of Electricity.” by Joseph
Priestly, inventer of soda water, and discoverer of oxygen (or dephlogisticated
air as he called it). Franklin and Priestly were both members of
the UK’s Lunar
Society and were in frequent correspondence. Franklin placed
multiple ‘Leyden Jars’ in series to increase their power,
calling them
a ‘battery’ comparing them with a ‘battery of cannons.’ The Leyden Jar
was invented in 1745 by German cleric Ewald Georg von Kleist, because
he thought electricity might be a liquid, and so he attempted to
‘bottle’ it. And it worked like a treat, even if the reasoning was
unsound. The Leyden Jar is filled with water or other fluid, and a
metal rod is is part submerged in the build and part extending out the
neck of the bottle. On some versions the inside and outside is lined
with foil. It would later be discovered that the electrical charges
were building up not within the fluid, but on the surface of the glass.
These Leyden Jars could be
made to spin cylinders using static electricity and perhaps some other
experiments, but mostly people were impressed by how they could be
electrically shocked when they touched it. Electricity was still a
mysterious force and there were no applications for it yet. The jars
supposedly generated up to 60,000 volts in short bursts, which meant
eventually people stopped wanting to touch them. Imagine being Benjamin
Franklin’s houseguest in the age of parlor tricks. “Hey, come here and
hold this..”
Ceramics and
pigments (coffee cup and Lego)
Electroceramics and Pigments
Many electrical engineers
are not aware of what a capacitor, or a resistor, or a diode, is made
of, or how they work; they only know their function as part of an
overall circuit design. There’s no shame in this; a mechanic knows how
to put a car together but they may not know how to make the parts. No
one person can know everything; it takes a world full of specialists to
create the magic of our modern day experience. For our purposes we must
demystify this subject because it is important for our story.
Ceramics are what these
components like this are most often made of. What’s a ceramic?
According to
wikipedia, it’s a “solid material comprising an inorganic compound of
metal or metalloid and non-metal with ionic or covalent bonds...”
Thanks wikipedia, that sounds cool and might make sense if you’re a
brainiac, but not helping to clarify things so much. The dictionary
definition of ceramics is even worse:
“made of clay and hardened by heat” and the dictionary definition of
‘clay’ is a “stiff, sticky fine-grained earth, typically yellow, red,
or bluish-gray in color and often forming an impermeable layer in the
soil. It can be molded when wet, and is dried and baked to make bricks,
pottery, and... ceramics.” And, we come full circle; according to the
dictionary, ceramics are made of clay, and clay makes
ceramics. Any more questions?
Let’s start with clay,
which we’ll call by its longer name, Aluminum Silicate Hydroxide.
You’ll
notice
that it has aluminum in the name, which is metal; it has some silicate,
which is silicon and oxygen; silicon being a metalloid, which means it
has ‘metal-ish’ qualities. It’s also got the word hydroxide at the end,
which is oxygen and hydrogen. Since it has ‘oxide’ at the end, we also
know it’s lost some electrons along the way.
More simply, we can say
that many or most ceramics are metal oxides.
Glass is made of silicon
dioxide, and shares some physical qualities and processing technique
with ceramics. Silicon is used as a semiconductor for microchips,
and
silicon is a ceramic, according to wikipedia’s snappy definition of it.
Other ceramics, which are also metal oxides, are also semiconductors,
such as titanium dioxide and zinc oxide. These
particular ‘electro
ceramics’ are of interest to us because they have some unusual
properties. As metals they were once conductive, but as oxides, they
are semi-conductive. Not all oxides are semiconductors, aluminum oxide
for example is an insulator, even though aluminum is a great conductor.
Besides titanium dioxide and zinc oxide being ceramics and
semiconductors, they are something else entirely: they are regular white
pigments.
The history of pigments
is
very interesting indeed, yet in some ways it is a short story. Stable
pigments are not that common in nature; when they are found they are
appropriately treasured and have been prized since antiquity. From
familiar pigment sources like indigo
to more unexpected sources such as seashells,
insects, and mummified
remains; everything at hand has been
tried. However industries require steady and reliable sources for
pigments on a large scale, and there are surprisingly few pigments to
choose
from. Most colors can be obtained by mixing a few key primary pigments.
Let’s take the history of
white pigments. At first we had chalk, like cavemen. This is calcium
carbonate, and it’s still used today on blackboards. Then we had lead white which was used for thousands of years
before the dangers became
apparent. Lead white was replaced by zinc oxide, and zinc oxide was replaced by titanium dioxide.
Those are
the only four choices for white pigment and all of them are derved from
metals; two of them are metal oxides, the other two are metal
carbonates, and carbonates contain hydrogen, oxygen, and carbon.
If you’re looking at
something right now that is white, perhaps a mug or something made of
plastic, then it almost certainly contains titanium dioxide. It’s in
ceramics,
plastic, food, toothpaste; whatever is white, that we wish to remain
white ie. a stable pigment. Zinc oxide is also in food, cosmetics, and
is an active UV-blocking ingredient in sunscreen, and the main
ingredient of calamine lotion. It really gets everywhere :-) Most of
these pigments are used for ink and paint, worldwide.
At the risk of sounding
like an informercial, that’s not all! Titanium Dioxide and Zinc Oxide
have some amazing qualities besides being white-colored semiconductors.
They are also photocatalytic. A catalyst
is something that facilitates
a chemical reaction without being consumed; a photocatalyst facilitates
a chemical reaction in the presence of light. In fact, the phenomenon
of photocatalysis was discovered first in titanium dioxide, and its
ability to split water molecules into oxygen and hydrogen in the
presence of sunlight. Titanium Dioxide is also used as a photocatalytic
antibacterial coating on some hospital equipment (thin enough to be
invisible and not white-colored); when it is exposed to light,
specifically UV, the photons excite the electrons in the titanium
dioxide into a more excited orbit, and they electrocute the germs and
mold on the surface. It can also be applied as a thin transparent layer
to make self-cleaning windows, by breaking up organic
matter with its
electrical charge when exposed to UV. You can see the electrons in
titanium dioxide (almost any white object) become excited and emit
photons when it is exposed to a UV blacklight - they fluoresce.
Notes for
progressive iterations of cell prototype
Piezoelectricity and Pyroelectricity
Zinc Oxide is also a
photocatalyst, but it is also piezoelectric
which means it produces an
electric charge when it experiences mechanical stress (when it is
bent); and it is also pyroelectric,
which means that it produces an
electric charge when it experiences changes in temperature.
Interestingly, bones are also both piezoelectric and pyroelectric too.
Since Titanium Dioxide is photocatalytic, and zinc oxide is
piezoelectric and pyroelectric, it’s difficult to know how much charge
is generated by which material in our prototypes, when they are both
part of the same
device, since the overall effect is cumulative and synergistic.
PVDF, or polyvinylidene
difluoride, is a polymer which is used widely for its piezoelectric
and
pyroelectric properties. They are used in solid-state weighing scales
(since
pressure changes its resistance it can be used to measure weight) and
is also used as a binder for electrodes for lithium-ion
batteries. We have used both PVDF and zinc oxide successfully for a dye-sensitized solar cell (DSSC) and an
all-inorganic perovskite solar
cell. Even though PVDF is a polymer, it comes in fine powder form,
and is extremely printable as a pigment
Titanium Dioxide and Zinc
Oxide are catalytic ingredients in both these types of solar cell
(DSSCs and PVSCs), but they are just a piece of the jigsaw. By
themselves they would not come close to being competitively efficient
in
terms of generating an electrical charge. As for the remaining
ingredients there are multiple schools of thought when it comes to
increasing the efficiency of the cell overall:
Dye-Sensitized
Solar Cells (DSSCs):
The name says it all, it’s
sensitized with dye. But why? Intuitively it would seem that black
materials would absorb more light and white materials would reflect
more light, and there is some truth to this, but it’s not the whole
story. Black materials can absorb visible light and emit
infrared;
infrared radiation from the black material appear might appear
invisible or
‘black’ to us, but it would appear white if we saw infrared light. On top of this,
infrared radiation is better at carrying heat energy than other
(visible) parts of the electromagnetic spectrum, so a black material
can experience
heat energy loss faster. Better absorbers are also better radiators.
Colors reflected that are
on the visible
spectrum are a clear indication that visible light is
being absorbed and not re-emitted or reflected. It helps to think about
what makes any material a particular color. We established that color
is dictated by electron states. If a material is red, it’s not just
because it reflects red light (it does do this, but white materials
also reflect red light, along with green and blue together, which
makes
it white). A red material reflects red light but also absorbs blue
light and
green light, which leaves only red light reflected. Instead of
reflecting the blue and green light, these blue and green photons are
absorbed by the electrons, which excites the electrons into a higher
and more excited orbit around the nucleus. If the electrons get excited
enough, they can move along a circuit like an electron pez-conga-line,
with a little encouragement from some appropriately doped
semiconductors (including titanium dioxide and zinc oxide) controlling
the direction of electron flow. Using different metals with different work
functions for the
electrodes (one biased for electron donating, and the other one biased
for electron receiving) further encourages electron flow in the desired
direction, increasing the current.
Our DSSC utilizes 3
different dyes mixed together; phthalocyanine blue, phthalocyanine
green and rhodamine 6G red. All these dyes emit light under
UV
radiation demonstrating their sensitivity to photons, and when combined
together they appear dark grey, but under UV light they emit red, green
and blue light to make an attractive white light. That’s not useful in
itself but it is a very unusual property to see in action. The dyes are
organic, which means they are based on a carbon
molecule, and are
therefore readily synthesized and available. That’s all organic means;
it doesn’t mean it’s safe to eat. In fact inorganic materials can be
safer, it’s case by case. These dyes are exceptionally stable.
Phthalocyanines are used for car paints, and Rhodamine G is used for
tracking river systems and in dye-lasers.
DSSCs are technically less
efficient than silicon solar cells at peak power but have the potential
to generate more energy overall because they do not have a
cut-off
point; they are able to generate electrical current in lower light
levels, even from artificial light sources, when silicone cells would
stop working completely.
Inorganic Perovskite solar cells (PVSCs):
Perovskite solar cells
emerged from the development of dye-sensitized solar cells. It is
natural to assume that it is the natural replacement, however both
fields are so young that there is no single authority on the subject.
The materials in a PVSC are all layered and differently doped inorganic
semiconductors sandwiched between two conducting electrodes of
different materials, much like a DSSC. It is similar to a DSSC, but it
doesn’t use dye as a photon absorber, it uses perovskites.
Perovskite, a little
confusingly, is the name of a mineral, calcium
titanate, but also
the name of any material with the same crystal structure (the
arrangement of the atoms) as calcium titanate. These materials
are typically metal oxides, semiconductors and ceramics, and some
naturally occurring mineral compounds.
Like
the word ‘quantum’
there is a reasonable amount of hype around perovskites. There is a lot
of press saying that lead is a critical ingredient to achieve maximum
efficiency but that’s not unanimous. The highest performing prototype
PVSC currently has lead in it, but the slight increase in performance
is far outweighed by the potential liabilities of manufacturing massive
volumes of lead-containing product.
It’s entirely possible to
add one type of cell to another and increase the efficiency of the
combined
cells. The effect is cumulative, the output is not limited to a
device’s
lowest performing element, as you would think intuitively. The highest
performing solar cells in the world are perovskite solar cells attached
to conventional silicon solar cells. Hybrids are a good thing. The same
happens with dog and animal breeding strangely, the phenomenon is
called
‘hybrid vigor.’ or ‘heterosis.’ The interface between two layers of
differently doped
semiconductors (where all the action happens, as we established earlier) is
called a ‘heterojunction.’
There is a great deal of
flexibility in the architecture of the cell; it comes down to
convenience and value - more important than technical efficiency over
surface area is the resulting cost per kilowatt hour; the only
technical measurement of consequence.
Electroluminescent
cell test
Electroluminescence and Phosphors
There are only so many ways
to make artificial light. It was a big accomplishment when
we did it
the first time with fire, and we tend to make a big deal every time we
come up with a new way of doing it, and rightfully so. It’s dark half
the time, and light is more important than just being able to read a
book at night. Light is security in the darkness; it is refuge; it is a
hallmark of civilization. After fire came the electric lightbulb of
course; Thomas Edison was not the first apparently; there
were
supposedly 22 people before him that also made lightbulbs.
However he
did do it best, which is why we associate him with the lightbulb
exclusively. There are dozens of variations on this same
lightbulb design, and then there are few alternative such as fluorescent
lamps :-( and of course we now have pleasant LEDs.
Electroluminescent (EL) cells are, by the
strictest definition, LEDs
(light emitting diodes) because they are diodes, and they emit light.
However the term is used to describe a different kind of design. LEDs
are small and very bright. EL lighting is any size, flat, and lower in
the brightness density as a result. It’s functionality as lamp is
improved with surface area. If EL lamps had the same light density as
LEDs, they would be blinding. A common example of an EL lamp
would be an exit sign in an office or hotel which remains on constantly
thanks to its reliability and low power requirements, and of course the
instrument panel in your car.
EL lighting architecture is
extremely similar to solar cells of all kinds, as well as capacitors;
they are
thin, wide and flat devices. The electrodes are flat and on the top and
the
bottom like bread in a sandwich; the active materials are the
filling in between them. In fact, an EL light is technically already a
capacitor
and a diode; they were born to be combined in some way it seems.
EL lamps are slightly
different to solar cells in that they do not require
electrons to flow through the circuit. They require the phosphor
layer’s electrons to be excited momentarily (by bashing them through a kind of membrane that is
the capacitor gap), before being allowed to
collapse back on themselves into their original orbit. When the
electrons collapse, they emit a flash of light, then they stop. EL
lamps require high voltages with low currents (low power overall)
alternating current only (AC) at a high frequency, to create as many
flashes over time as possible to create a continuous light. The EL
lamps in digital watches had tiny transformers in them to output 600
volts from their batteries. A stun gun is able to produce 100k volts
from a 9V battery; the current is reduced accordingly. It is still
enough to create a much larger electric ‘arc’
because of the high
voltage. Also, a stun gun hurts more when you touch it, than a 9V
battery :-) All EL lamps require a small transformer or dedicated power
supply to function. These can be powered by 9 volt or AA batteries, or
for a large number of EL lamps, a neon-light power supply would perform
the same function with more power.
Phosphors
are a group of
materials that emit photons when their electrons are excited by an
increased electric charge, or if another electron from an outside
source collides with it, or passes through it. An electron gun in a cathode
ray tube
television (CRT) works this way. In a CRT the electron
gun fires electrons straight towards the viewers’ eyeballs and brain,
but on the way to their destination, they excite the electrons within
the phosphors
that are embedded in the television screen, creating pretty pictures to
distract us while electrons turn our brains to jelly. Phosphors still exist in modern flat
televisions and telephone screens
and any kind of digital display. There are no phosphors that emit white
light; they generally emit a narrow spectrum (a single color) and multiple types of phosphor with multiple types of
dopants to achieve a
full spectrum white. Phosphors are made of ‘transition metals’ which
includes some metal oxides. Metal-doped Zinc sulfide is the classic
electroluminescent phosphor. They all have their various and
characteristic colors which can be mixed together to provide the
desired hue. The recipe for the phosphors in old black & white
televisions, is zinc sulfide and yttrium oxide doped with silver,
aluminum and copper. After 70 years of the technology, may of the
recipes are now known, but the EL industry is not forthcoming with
their application techniques and trade secrets, understandably. However
this means the entire field of EL is still shrouded in mystery and
there is not even a consensus on exactly why the mechanism behind
electroluminescence works, and not much on how.
3D printed
patterns for TWP connectors
The Ancient Art of Metal Casting
The oldest known metal casting
in history is a copper frog, 3200 BC, cast in Mesopotamia.
China has been casting since at least 1300 BC. India since 500 AD.
Since none of us were there, these dates might be completely
inaccurate,
but we can at least establish that humanity has been casting for a long
time; longer than we’ve been counting to ten (earliest evidence of
decimal system is 3100 BC, in Egypt, whereas Mesopotamians had a
base 60 system, circa 3400). Again, I wasn’t there, but that’s the
consensus.
In
that time, we’ve had ample opportunity to establish techniques and
methods for best practice. There are multiple variations of metal
casting,
but they are similar in the sense that it involves pouring molten metal
into a fire-and-heat-proof mold, such as sand or clay or both mixed
together.
The casting process
involves making patterns. Patterns are a ‘positive’ (not a
‘negative’ like photograph film) of the final
shape; that is, it
resembles the final piece being cast. Each cast object requires
at least two patterns, one for each side of the object. Those patterns
of both sides of the object are used to make an impression into a
sand/clay mixture and then removed, leaving a negative impression in
the sand (which contains some clay). Those two ‘sides’ are put ogether
to make a single mold which molten metal is poured into. The sand mold
can
then be broken apart leaving a single piece of cast metal, which then
has to be finished and polished. If the cast metal is to have a hollow
core, a negative pattern of the hollow core must be made to create a
positive cast of the core made of sand, and this sand (clay helps it
stay together) core is then placed inside the main negative sand cast
before molten metal is poured into it.
Once the patterns exist,
they become templates that can be used to cast items ad infinitum.
3D printers
that remind me of a Spinning
Jenny. My daughter calls them, technically correctly, the ‘robots’
3D Printing Casting Patterns
Casting is ancient, but
sculpture is even older still. Sculptures have been found in Germany that
are approximately 40,000 years old. It’s so simple in principle,
even children are capable of it.
In order to make an
impression into sand for sand-casting, that very
first pattern has to be sculpted. The pattern is made traditionally by
hand-carving a hard but workable material, such as wood. By the nature
of the process, this first stage takes time, but castings
from the pattern can be made quickly and are mass-producible.
Wood
is traditionally used
to make patterns, but plastic can also be
used, specifically in our case, 3D printed parts. TWP has ten branch
connector patterns (20 halves), each with several critical dimensions;
it would require
several hundreds, possibly thousands of hours of skilled labor to
hand-sculpt
and finish. 3D printed parts are faster, more accurate, and
dimensionally consistent.
3D printing is only decades
old but has quickly matured to a point
where the benefits are undeniable; it has permitted previously
unobtainable or unrealizable concepts to be manifestable, and quickly.
It allows for countless iterations of prototypes that would otherwise
be impossible due to cost and time restraints.
Machined aluminum connectors
The Renaissance’s Printing Press
Johannes
Gutenberg invented
the printing press
in 1440. The
emergence of this technology at once meant that all accounts after that
point became more reliable and indelible; it was practically the
beginning of
crystallization of records. If only a single book in an entire print
run survives time, the matter of record is preserved. It can be
reproduced and shared again, ad infinitum. It is not only of benefit to
the fidelity of the information, but it is of benefit to all people
that would now have access to the body of humanity’s experience, simply
because of high volume production capabilities and subsequent low cost.
Most of the information in this body of text is available because it
was printed at some point in history.
It’s difficult to fully
appreciate the impact of the printing press on humanity’s quest for
knowledge and understanding, unless we imagine what it would be like
without it. Before the printing press, knowledge was hand-written,
and
unreproducible without writing it again for each subsequent copy;
greater amounts of information meant the greater the obstacle to its
reproduction and therefore propagation.
For instance, ‘Journey to
the West’ is a 16th century Chinese novel written by Wu Cheng'en.
The
story is about a Buddhist monk named Tripitaka who is instructed to
make a pilgrimage to obtain the Buddhist scriptures from India. It is a
fantastic story full of magic and monsters, but is inspired by real
life events about a Chinese monk in the 7th century who travelled to
India to obtain better translations of Buddhist scriptures. The
Buddhist scriptures are called ‘The
Tripitaka’ and the body of work is
so large, it takes several years to read from beginning to end, let
alone translate. (it’s not even completely translated into English
yet). Now imagine there are no photocopiers, and you have to
not only read it, understand it, and translate it, but also write it
all down again. Then you have to carry it back to China on horseback.
The real Buddhist priest spent 13 years on his pilgrimage. To say that
information was previously more costly and harder to obtain, would be a
massive understatement. Before the printing press, handwritten and
illustrated books containing some of the secrets of the universe must
have been more valuable than gold, jewels, or even palaces. They were hand-painted by artisans with rare pigments, adorned
with jewels, and had gilded pages; they must have seemed
magical and precious beyond riches.
According to National
Geographic, the printing press is the most important invention in
history, so, well done, overachieving Johannes Gutenberg; although
National Geographic would say that; they are a printed magazine after
all. Also, according to National Geographic, the lightbulb is the
second most
important invention in history. Interestingly, we are combining the
two; we are producing a light source that can be made with a printing
press.
The pigments which were
mentioned earlier; which are also ceramics; which are also
electroceramics; which are also semiconductors; which are also pigments
used in wall
paint, oil paints, plastics, dish ware, make-up, and food etc. are the
exact same pigments used the different printing industries; it
is only the type of solvent and viscosity that vary. This means that
besides being able to print images and words, print presses are capable
of producing intelligent and solid-state functional devices without any
retooling or special equipment; all the engineering is executed via
circuit design and material/pigment design.
Sik-screening
station
Silk Screen Printing Prototypes
Since all pigments are the
same in all inks and paints, the testing
method for print functionality does not have to be the same as that
used for manufacturing. That is, it is impossible to efficiently make a
single print on an offset printing press; it can take hundreds of
sheets in order to ’make ready’ the press so that it will print
correctly. That would mean 100s:1 wastage for every single iteration. Silk
screen printing is a process whereby it is efficient to make a
single print at a time, necessary when making repeated
iterations for experimentation for R&D.
Although the Chinese have
been silk screen printing for a thousand
years, it has only been popular in the west for about a hundred years,
since the introduction of light-sensitive emulsions; one could say it
took a remarkably long time to become popular.
Prototype
electroluminescent cell
Salt Batteries and Supercapacitors
As mentioned previously,
the first ever battery was the voltaic pile, made by Alessandro Volta
in 1799, and that this battery is technically a capacitor. Before
Volta, it was Luigi Galvani in 1780 that first discovered the
electrical phenomenon that led to the voltaic pile. He found that if he
put two different metals together, one made of copper, the other zinc
(what we would now call electrodes, with different work
functions)
and then placed those metals onto the leg of a frog,
that the frog’s leg would move. He called it animal electricity. A
charge was built up on the metal rods, and they discharged into the
frog’s leg causing the muscles to contract. In fact the phenomenon
requires an electrolyte to be present, which is contained within the
frog’s leg; they are the same electrolytes we have in our body: sodium,
potassium, calcium, bicarbonate, magnesium, chloride and phosphate.
Alessandro Volta developed
this idea and responded with the voltaic
pile, a non-biological battery
made of alternating zinc and copper discs interleaved with paper soaked
in saltwater (which is an electrolyte solution). His accomplishment was
achieving this
without the use of a frog in any way. In an example of an early energy
arms race, Luigi Galvani believed that electricity was a phenomenon
exclusive to living (or previously living) organisms, and responded by
making a 100% biological battery, made
from a number of dead frogs in
series. Volta won that race, as evidenced by the fact that we do
not
insert frogs into our remote controls and our smoke alarms; nor do we
all live
in a frog-matrix-like world that provides for all our energy needs.
One of the common
denominators in Volta’s voltaic pile and Galvani’s frog battery, is the
electrolyte. Batteries require electrolytes, and
have done since the
very first frog battery. Salts dissolved in a fluid eg. water or blood,
makes an electrolyte solution. Sodium
is a volatile and unstable metal until it
teams up with chloride, iodide
or a sulfate,
and then becomes a ‘salt’;
likewise with calcium, magnesium
and potassium.
Lithium,
sodium and potassium are alkaline;
potassium is the alkaline
referred to in ‘alkaline batteries.’ The lithium manganese oxide in
lithium batteries, is technically a salt; salts comprise of cations and
anions; lithium is the cation and oxide is the anion. Many lithium
salts are used as medications, including lithium carbonate, lithium
acetate, lithium sulfate, lithium citrate, lithium orotate, and lithium
gluconate.
Interesting fact about
lithium: along with boron (an essential ingredient for life on Earth)
and beryllium,
lithium cannot be made inside stars, because these
elements
are intermediate steps in other fusion reactions; they are the only
elements that get ‘skipped.’ Only after
the stars explode, and the
heavier elements are then exposed to the intense radiation of a black
hole or neutron star, can these remaining elements be created. It’s a
long and winding road to get to where we are.
In the interest of clarity,
we should establish the difference between batteries and capacitors...
zzz... sorry but it is an important distinction, albeit with little visible consequence to the consumer; they both
provide power on demand, they just do it in different ways,
which results in different behaviors. Ultimately, in terms of
language, anything that provides electrical power will be referred to
by people as a ‘battery’ even if this is not technically accurate. So,
here we go, hold on tight for this next part, we’re almost finished..
A circuit with a capacitor
actually has a gap in the circuit; a tiny gap, as we've covered, where
opposite charges (electrons and electron holes) can build up on either
side of this gap. No charged particles actually cross this gap, so
there is not a flow of electrons or holes, they merely build up at
these contact plates, and when they are discharged, they leave the way
they came. Imagine a rubber membrane in a water pipe. You can force
water into the pipe, and that water will exert pressure on the
membrane, allowing force to pass through the membrane, but not allowing
water to pass through it (electrons in our case). The membrane is under
tension, so when
pressure on the water is released, the stored energy in the rubber
membrane pushes the water back out the way it came in. This is actually
an established analogy of what happens with electrons
and holes on both
sides of this ‘gap.’ In reality this gap can be the gaps within a
porous material, such as carbon, or the gap between two strips of foil
rolled up with some paper in between, or a miniature maze-like
network
where the two contact plates run parallel to each other to obtain the
maximum surface are possible. Surface area can be increased as much as
100,000 fold, just by using a textured surface rather than a smooth one.
In contrast there is no gap
in the circuit with a chemical battery. The electrical circuit, ie. the
pathway for electrons and electron holes, is unhindered; the circuit
passes though the electrolyte, which is usually liquid or liquid-like,
like saltwater. The electrical ‘charge’ is contained and transmitted
within this
electrolyte matrix. The electrolyte contains both positively and
negatively charged particles (ions) which attract and transport both
electrons and electron holes; like tiny magnets in which opposite poles
attract.
The practical difference is
that capacitors can charge almost instantly, and discharge completely
just as instantly. This is actually quite desirable, but in some ways,
less
efficient than a chemical battery.
There are hybrids being developed, and there are some that
believe that
the future lies in extremely high surface area supercapacitors
that can
charge in an instant, but will discharge slowly and steadily. Much like
the various photovoltaic cells, there are multiple methods to store an
electric charge once
you understand the mechanism. (Insert frog joke.)
Prototype
electroluminescent cell
Solid-state Electrolytes
Car
batteries have liquid
electrolytes, and cannot be turned upside down otherwise they leak.
Alkaline batteries are called dry cells
because they don’t have a
liquid electrolyte, but they still use a pastes or gels which arguably
are not that dry, and still have the potential to explode if the
battery is overcharged, discharged or heated.
In both Alessandro Volta’s
voltaic pile battery, and Luigi Galvani’s
frog battery, the electrolyte is liquid, or at least moist, or soggy.
This is still the case, and modern batteries require a sealed enclosure
to contain these wet electrolytes, or they would quickly dry out and
cease to function.
Alessandro Volta
experimented with his own pile battery in which the
salt water had dried up, and noticed that it still kind of worked, but
it was Johann Wilhelm Ritter was the first to publish, in
an “albeit
obscure journal” (thanks again, Johannes Gutenberg) the phenomenon of
the ‘dry’ battery pile in 1802, three years after Volta invented the
pile. Ten years after that in 1812, Giuseppe
Zamboni invented the
‘Zamboni
pile’ which was designed to be a dry battery based on Johann
Wilhelm Ritter and others’ observations. However, it did utilize honey.
Is that cheating a little? It’s true that honey does not dry out nearly
as fast as water, but it’s still wet, or at least I wouldn’t exactly
call it dry, or solid. (Honey is reputed to un-spoilable; 3000 year-old
honey in the Egyptian pyramids was apparently still “perfectly edible”)
The somewhat-dry Zamboni was capable of producing a high voltage, but a
low current. It turns out that a less ‘mobile’ electrolyte reduced the
current, but not the voltage; a Zamboni pile is still capable of
producing thousands of volts, and they were still being manufactured
until about 30 years ago for specialized and military applications. A
pair of Zamboni batteries power the “Oxford Electric Bell” which has
been ringing continuously since 1840; it is the Guinness World Recorder
as "the world's most durable battery.”
There are several salt-themed batteries being developed; sodium batteries, salt
water batteries, molten salt batteries and more. I say salt-themed,
because all batteries
would seem to require some kind of salt, of which there are many
different kinds to choose from. Salt is defined as a compound (a combination of
elements) with equal or “related numbers” of anions
and cations
(negatively and positively charged atoms or molecules).
Salts
that we use in our bodies are sodium chloride, potassium iodide etc, as
we have covered. Just sodium by itself isn’t technically ‘salt,’
chemically speaking (pure sodium
is a metal that combusts when exposed
to air). Salts are crystalline compounds when they’re dry, but when
dissolved in a medium, these anions and cations ‘disassociate’ freeing
them to hold a ‘charge’ from other sources, and an allows an electric
current to flow within the medium. If a salt solution dries up, the
salt recrystallizes as the anions and cations re-attract and hold onto
one another; at this point they are not available to perform the same
function as when they are dissolved and separate. It’s worth noting
that the elements that make up a ‘salt’ are on the opposite ends of Linus Pauling’s electronegativity
scale,
so they’re really attracted to each other as a compound, when they’re
not dissolved in a fluid. In theory if sodium was separated from sodium
chloride, it would burst
into flames in contact with water.
The entire field of
solid-state electrolytes (SSE) as far as I can
observe, is disparate and divided. It’s not exactly a glamorous
subject, not like quantum physics or rocket science; it is a blindspot
of sorts. SSEs have been described as the “holy grail” for battery
development, even though technically speaking, the second battery ever
invented uses an SSE and has been operating without interruption since
1840. There are numerous parties that have produced, or are developing SSEs. IBM is developing a solid-state ‘quantum’ battery
“made from materials that can be extracted from the sea, which
outperforms today’s technology across the board,” This could be a word
for word description of what we have achieved so far with our
prototype; our functional solid-state electrolytes are also obtainable
from the ocean; sodium iodide and potassium
iodide, which are both used as medicine.
There are few
incentives for the big battery producers to change their existing
business
model, since the battery market as it currently exists is thriving. I’m
not suggesting any kind of conspiracy,
it’s just that a change of state
requires inducement, for either humans or electrons.
TWP Anodized Aluminum Components
TWP Research and Development
Congratulations, the
science and history lecture is over, you got to the end of it. Now
let’s try to have a Mr. Miyagi ‘Wax-on,
wax-off’ moment. The following should make
much more sense to you than if you skipped everything up until this
point.
As of May 2020, we have
designed and built the following:
• Functional prototype for
a printable DSSC (dye-sensitized solar cell)
(that also converts UV into full spectrum visible white light)
• Functional prototype printable PVSC (perovskite solar cell)
(Both DSSC and PVSC are also piezoelectric and pyroelectric)
• Functional prototype for a printable EL cell (electroluminescent cell)
• Functional prototype for a printable, solid-state electrolyte*
• All TWP’s 3D printed tree branch connector patterns
• Combined DSSC with solid-state electrolyte**
**We have produced a
functional
prototype of a pigment-printable, dye-sensitized cell which is at the
same time,
a photovoltaic, piezoelectric, and pyroelectric, self-charging,
solid-state battery. *The electrolyte is a
combination of sodium iodide and potassium iodide dissolved into a
water-based flexible resin polymer
commonly used as a pigment binder
for printing onto fabrics. Solid electrolytes of this nature are called
‘fast ion conductors.’ We measure a 0.6V open circuit voltage from an
area the size of a large stamp.
Only half the cells
electroluminesce on the prototypes: The functionality and uniformity of
the electroluminescent layer is sensitive to 1/1000th of an inch. Any
variation in thickness, gap, or piercing of the layers during
fabrication, can be critical. The next stage of prototype needs to be
made on a small-scale printing-press; however before this can be done
multiple iterations were by hand (just as any large-scale print-job
requires a ‘proof’ before printing high volumes) with the expectation
that not all the cells will function, exactly because they are made by
hand and not a machine; it is next to possible to flawlessly reproduce
the effect of a camera, photocopier or printing press with a paint
brush. However these early-stage prototypes demonstrate proof of
concept, enough to begin printing on a scaled-down lithography press,
using the same techniques exactly as traditional large-scale
lithography presses. The prototypes demonstrate that when the cell
design and circuit is applied uniformly, and without errors (much like
an impression by a printing press) there is functionality.
Other points worth noting:
• The EL cell is rated for
greater power; at low light/power levels like
we're using to test prototypes, the light is blue, but appears white
with greater brightness/more power.
• LIke a neon light, EL
requires a
transformer to convert low voltage DC into high voltage, high frequency
AC. The power source we are using for hand-made prototypes with
uninsulated circuits is a 9V battery, for safety.
• The EL cell, the
solid-state electrolyte
cell, and solar cell, all utilize the same circuit; only the materials
are different. The circuit design is a template for countless
apllcations that require increased surface area.
• The solid-electrolyte
cell and the DSSC utilize graphite, which is the traditional material
for electrodes in some batteries. When graphite is subjected to
sufficient shear forces (such as a blender) graphene is produced. In
fact the graphene that won the Nobel Prize was harvested from graphite
using scotch tape. When graphite is blended and distributed uniformly
within a medium with sufficient viscosity at proportions that yied the
optimum percolation
level, a graphene network within the medium can be created.
Independently, the terms ‘graphene’ and ‘perovskite’ are used heavily
as marketing tools by battery and solar cell developers.
12 months of research and
development has been conducted by myself, and
co-funded by Kevin Davis who works at a famous space agency here
in
Pasadena, and is the drill-operator for a rover
currently on Mars.
Implementation
The next stage for TWP is
to build a showcase demonstrating both the mounting structure and the
energy cells in combination.
Prototype construction of the mounting system is complete, patent application has been filed.
— Michael Simon Toon
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