yes
storytelling 2...... nathan
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pervoskite extension
Basic Summary
Perovskite solar cells are
a new type of cell that are replacing the silicon based ones. Perovskite
compounds generally consist of a hybrid organic-inorganic lead or tin
halide-based material, which are cheap to produce and easy to manufacture. As
of 2016, the solar cell efficiency rate has risen to 22.1% - an all-time high -
from 3.8% efficiency back in 2009. Perovskite solar cells have gained mass
appeal from a commercial standpoint because of their potential to reach even
higher solar efficiency and their substantially low production costs. Companies
are planning to release perovskite solar cell modules to the market by 2017.
These new forms of solar cells are beneficial to basically everybody because
they're a new and cheaper form of renewable energy - hopefully meaning it's
affordable for most people to purchase. With the establishment of these
perovskite cells, their effects should reduce the amount of global warming
occurring, which will save the earth in which we inhabit.
What is a perovskite?1
The term perovskite and
perovskite structure are often used interchangeably. Technically, perovskite is
a type of mineral that was first found in the Ural Mountains and named after
Lev Perovski who was the founder of the Russian Geographical Society. A
perovskite structure is any compound that has the same structure as the
perovskite mineral.
True perovskite (the
mineral) is formed of calcium, titanium and oxygen in the form CaTiO3.
Meanwhile, a perovskite structure is anything that has the generic form ABX3
and the same crystallographic structure as perovskite (the mineral). However,
since most people in the solar cell world aren’t involved with minerals and
geology, perovskite and perovskite structure are used interchangeably.
The simplest way to think
about a perovskite is as a large atomic or molecular cation (positively
charged) of type A in the centre of a cube. The corners of the cube are then
occupied by atoms B (also positively charged cations) and the faces of the cube
are occupied by a smaller atom X with negative charge (anion).
Perovskite performance (sourced from Helmholtz
Center in Berlin)2
Scientists from the Federal Polytechnic
Institute in Lausanne (EPFL), Switzerland, and of Helmholtz Center Berlin-Institute
for Solar Fuels have now uncovered the mechanism by which these novel
light-absorbing semiconductors transfer electrons along their surface. They
examined perovskite based solar cells with different architectures with time
resolved spectroscopy techniques. Their results open the way to the design of
photovoltaic converters with improved efficiency.
The groups of Michael Gratzel and
Jaques E. Moser at EPFL, working with the team of Roel van de Krol at
HZB-Institute for Solar Fuels, have used time-resolved spectroscopy techniques
to determine how charges move across perovskite surfaces. The researchers
worked on various cell architectures, using either semiconducting titanium
dioxide or insulating aluminum trioxide films. Both porous films were
impregnated with lead iodide perovskite (CH3NH3PbI3)
and an organic “hole-transporting material”, which helps extracting positive
charges following light absorption. The time-resolved techniques included
ultrafast laser spectroscopy and microwave photoconductivity.
The results showed two main dynamics.
First, that charge separation, the flow of electrical charges after sunlight
reaches the perovskite light-absorber, takes place through electron transfer at
both junctions with titanium dioxide and the hole-transporting material on a
sub-picosecond timescale. “Secondly, we could measure by microwave
photoconductivity that charge recombination was significantly slower for
titanium oxide films rather than aluminum ones,” Dennis Friedrich from the van
de Krol Team points out. Charge recombination is a detrimental process wasting
the converted energy into heat and thus reducing the overall efficiency of the
solar cell.”
The authors state
that lead halide perovskites constitute unique semiconductor materials in solar
cells, allowing ultrafast transfer of electrons and positive charges at two
junctions simultaneously and transporting both types of charge carriers quite
efficiently. In addition, their findings show a clear advantage of the
architecture based on titanium dioxide films and hole-transporting materials.
How solar cells work
Cells made from a semiconductor
material such as silicon absorb a portion of light through a photovoltatic cell
(PV). Light photon energy is knocked loose allowing them to move freely which
forms a current. Metal contacts on the top and bottom of PV cells draw off the
current to use externally as power.
Practical Applications
Toys
Watches
Calculators
Water pumps
Portable power supplies
Satellites
Electric fences
Anything that silicon based solar
panels are implemented in already
Story Line
Perovskite cells dominate the
energy market. All sources of energy are either far behind or obsolete leading
to their decline. The world slowly re-cooperates from the pollution caused by
previous modes of energy.
Scenario 1: To heighten the
efficiency rates of perovskite cells, scientists attempt to experiment with
different types of combinations. The material they tamper with is highly
unstable, meaning they’re putting themselves in a high risk high reward
situation depending on the results. Like in any movie, they somehow fuck up and
assess the miscalculations. Their conductions essentially create a chemical
reaction so powerful that it wipes out all the power in the hemisphere. Though
no one is hurt, the remaining power is all they have left.
Scenario 2: The perovskite
cells are first implemented into all satellite services in the orbit. Though
companies using perovskite cells gathered efficiency results, they didn’t
calculate the life-span of the materials and they begin to decay rather
quickly. With no time to fix them, most services that people use experience
down time and they all riot due to withdrawal.
Scenario 3: The sun dies or
disappears suddenly. Desperate to survive, the scientists producing these
modules come together and attempt to sustain life with the remaining power
stored within the perovskite cells only for themselves while everyone else
struggles to survive without sunlight and proper climate acclimation.
Sources
1 https://www.ossila.com/pages/perovskites-and-perovskite-solar-cells-an-introduction
2 http://www.helmholtz-berlin.de/pubbin/news_seite?nid=13908&sprache=en&typoid=49880
Friday, September 30, 2016
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