storytelling 2...... nathan: 2016

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

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.