What are perovskite?
Perovskites are a class of materials that share a similar structure, which display a myriad of exciting properties like superconductivity, magnetoresistance and more. These easily synthesized materials are considered the future of solar cells, as their distinctive structure makes them perfect for enabling low-cost, efficient photovoltaics. They are also predicted to play a role in next-gen electric vehicle batteries, sensors, lasers and much more.
How does the PV market look today?
In general, Photovoltaic (PV) technologies can be viewed as divided into two main categories: wafer-based PV (also called 1st generation PVs) and thin-film cell PVs. Traditional crystalline silicon (c-Si) cells (both single crystalline silicon and multi-crystalline silicon) and gallium arsenide (GaAs) cells belong to the wafer-based PVs, with c-Si cells dominating the current PV market (about 90% market share) and GaAs exhibiting the highest efficiency.
Thin-film cells normally absorb light more efficiently than silicon, allowing the use of extremely thin films. Cadmium telluride (CdTe) technology has been successfully commercialized, with more than 20% cell efficiency and 17.5% module efficiency record and such cells currently hold about 5% of the total market. Other commercial thin-film technologies include hydrogenated amorphous silicon (a-Si:H) and copper indium gallium (di)selenide (CIGS) cells, taking approximately 2% market share each today. Copper zinc tin sulphide technology has been under R&D for years and will probably require some time until actual commercialization.
What is a perovskite solar cell?
An emerging thin-film PV class is being formed, also called 3rd generation PVs, which refers to PVs using technologies that have the potential to overcome current efficiency and performance limits or are based on novel materials. This 3rd generation of PVs includes DSSC, organic photovoltaic (OPV), quantum dot (QD) PV and perovskite PV.
A perovskite solar cell is a type of solar cell which includes a perovskite structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer. Perovskite materials such as methylammonium lead halides are cheap to produce and relatively simple to manufacture. Perovskites possess intrinsic properties like broad absorption spectrum, fast charge separation, long transport distance of electrons and holes, long carrier separation lifetime, and more, that make them very promising materials for solid-state solar cells.
Perovskite solar cells are, without a doubt, the rising star in the field of photovoltaics. They are causing excitement within the solar power industry with their ability to absorb light across almost all visible wavelengths, exceptional power conversion efficiencies already exceeding 20% in the lab, and relative ease of fabrication. Perovskite solar cells still face several challenge, but much work is put into facing them and some companies, are already talking about commercializing them in the near future.
What are the advantages of Perovskite solar cells?
Put simply, perovskite solar cells aim to increase the efficiency and lower the cost of solar energy. Perovskite PVs indeed hold promise for high efficiencies, as well as low potential material & reduced processing costs. A big advantage perovskite PVs have over conventional solar technology is that they can react to various different wavelengths of light, which lets them convert more of the sunlight that reaches them into electricity.
Moreover, they offer flexibility, semi-transparency, tailored form factors, light-weight and more. Naturally, electronics designers and researchers are certain that such characteristics will open up many more applications for solar cells.
What is holding perovskite PVs back?
Despite its great potential, perovskite solar cell technology is still in the early stages of commercialization compared with other mature solar technologies as there are a number of concerns remaining.
One problem is their overall cost (for several reasons, mainly since currently the most common electrode material in perovskite solar cells is gold), and another is that cheaper perovskite solar cells have a short lifespan. Perovskite PVs also deteriorate rapidly in the presence of moisture and the decay products attack metal electrodes. Heavy encapsulation to protect perovskite can add to the cell cost and weight. Scaling up is another issue - reported high efficiency ratings have been achieved using small cells, which is great for lab testing, but too small to be used in an actual solar panel.
A major issue is toxicity - a substance called PbI is one of the breakdown products of perovskite. This is known to be toxic and there are concerns that it may be carcinogenic (although this is still an unproven point). Also, many perovskite cells use lead, a massive pollutant. Researchers are constantly seeking substitutions, and have already made working cells using tin instead. (with efficiency at only 6%, but improvements will surely follow).
While major challenges indeed exist, perovskite solar cells are still touted as the PV technology of the future, and much development work and research are put into making this a reality. Scientists and companies are working towards increasing efficiency and stability, prolonging lifetime and replacing toxic materials with safer ones. Researchers are also looking at the benefits of combining perovskites with other technologies, like silicon for example, to create what is referred to as “tandem cells”.
Commercial activity in the field of perovskite PV
In September 2015, Australia-based organic PV and perovskite solar cell (PSC) developer Dyesol declared a major breakthrough in perovskite stability for solar applications. Dyesol claims to have made a significant breakthrough on small perovskite solar cells, with “meaningful numbers” of 10% efficient strip cells exhibiting less than 10% relative degradation when exposed to continuous light soaking for over 1000 hours. Dyesol was also awarded a $0.5 million grant from the Australian Renewable Energy Agency (ARENA) to commercialize an innovative, very high efficiency perovskite solar cell.
Also in 2015, Saule Technologies signed an investment deal with Hideo Sawada, a Japanese investment company. Saule aims to combine perovskite solar cells with other currently available products, and this investment agreement came only a year after the company was launched.
The latest perovskite solar news:
Researchers in Germany have sent perovskite and organic solar cells on a rocket into space. The solar cells withstood the extreme conditions in space, producing power from direct sunlight and reflective light from the Earth's surface. The work sets the foundation for future near-Earth applications as well as potential deep space missions.
One of the goals for space missions is to minimize the weight of equipment that the rocket carries. While current inorganic silicon solar panels used in space missions and satellites have high efficiencies, they are also very heavy and rigid. The emerging technology of hybrid perovskite and organic solar cells that are incredibly light and flexible becomes an ideal candidate for future applications.
Saule Technologies to develop perovskite solar module enabled IOT asset tracking for wildlife conservation
An animal-tracking system by Saule Technologies will support the monitoring of European bison in Ukraine. Local partner World Wide Fund for Nature (WWF) Ukraine, WWF Poland and Saule Technologies will cooperate on the “Perovskite Solar Module Enabled IOT Asset Tracking for Wildlife Conservation” initiative under the Challenge Fund: Polish Solutions for SDGs Fund, with the financial support of the Ministry of Foreign Affairs of the Republic of Poland.
Bohdan Vykhor, PhD, Wildlife Programme manager at the WWF Ukraine, explains that bison population recovery is an ongoing process. “The species was reintroduced to various areas in Europe with significant efforts from different wildlife conservation programs (WWF, LHI, COA, IUCN, LIFE EU) and great work should be done in the future. We need to connect the free moving bison population divided across Europe and support natural gene flow. Using tracking systems on captive animals is an important element for understanding their behavior in the natural environment, ecological corridors and crucial habitats for different stages of their life cycle - so vital data is key to the success of species conservations.”
Scientists at the University of North Carolina (UNC) have taken on a known perovskite issue - the annealing (heating and slow cooling) process. Many fabrication processes take too long, presenting a significant bottleneck in mass production. The UNC scientists estimate that for long annealing times to keep up with the speed at which perovskites films are produced, manufacturers would need a 500-meter-long oven.
The UNC scientists say that cutting this annealing process down to three minutes at 100o C could lead to better performance. The group puts this down to a previously unknown de-doping process within the perovskite, which ultimately leads to lower recombination losses and better efficiency.
Reports out of China suggest that a perovskite photovoltaic cell production line has gone into production in Quzhou, east China's Zhejiang Province.
The 40-hectare factory was reportedly funded by Microquanta Semiconductor and expected to produce more than 200,000 square meters of photovoltaic glass before the end of 2020.
Researchers at Cornell University and University of Cambridge have analyzed the overall environmental impact of two types of solar panels, comparing these against panels made with crystalline silicon wafers – the current industry standard.
The team found that a solar panel made from two layers of perovskite requires a smaller total energy input and results in fewer carbon emissions. The panel, a perovskite-perovskite tandem, contains two layers of the material on top of each other, each optimized to absorb a section of the electromagnetic spectrum.