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.
In October 2020, Saule launched sunbreaker lamellas equipped with perovskite solar cells. The product is planned to soon be marketed across across Europe and potentially go global after that.
In August 2020, reports out of China suggested 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.
In September 2020, Oxford PV's Professor Henry Snaith stated that the Company's perovskite-based solar cells are scheduled to go on sale next year, probably by mid 2021. These will be perovskite solar cells integrated with standard silicon solar cells.
The latest perovskite solar news:
Researchers from Princeton University and the King Abdullah University of Science and Technology (KAUST) have connected silicon solar cells with perovskite ones in a tandem solar cell to not only boost overall efficiency, but also to strengthen stability. The results show that the connection protects the frail perovskite solar cell from voltage-induced breakdown while attaining greater efficiencies than either cell can achieve on its own.
The team demonstrated that the tested perovskite/silicon tandem devices are considerably more resilient against reverse bias compared with perovskite single-junction devices. The origin of such improved stability stems from the low reverse-bias diode current of the silicon subcell. This translates to dropping most of the voltage over the silicon subcell, where such a favorable voltage distribution protects the perovskite subcell from reverse-bias-induced degradation.
Graphitic materials supplier First Graphene has announced an R&D collaboration with Greatcell Energy, trading as Halocell Energy, and the Queensland University of Technology (QUT) to commercialize perovskite solar cell fabrication. The project has received a Cooperative Research Centers Project (CRC-P) grant worth over AUD$2 million (around $USD1,300,000).
The research and development project is intended to commercialize ultra-low-cost, flexible perovskite solar cell fabrication using Halocell’s roll-to-roll production process at the company’s Wagga Wagga plant, First Graphene said in an announcement. Through the project, First Graphene plans to develop cost-effective graphene-based electrode replacements for high-cost conductor materials, such as gold and silver, used in cell manufacturing.
U.S-based retail solar brand Grape Solar has announced that it will be going into the perovskite PV R&D field, as it appointed Dr. Leon Dong as its head of the newly formed Solar Technology Research Center (STRC) in Eugene, Oregon.
"This is a historical moment for us. Solar technology has improved significantly in the last decade, from efficiency and cost point of view, however, little has changed in terms of its form factor. The market demands for more flexible, lightweight, even more colorful solar products. We envision a future that would bring these kinds of technology to live in the next few years as the industry advances, and Grape Solar wants to excel in bringing new and improved technology products to our customers by making them in the United States. To achieve this goal, we need many young talents. Leon possesses the scientist mindset in the purest sense, which is rare to find these days." Commented Ocean Yuan, CEO of Grape Solar.
Researchers from Japan's Tokyo Institute of Technology, University of Oxford in the UK and Colorado State University in the U.S have shown that α-FAPbI3, a promising solar cell material with a cubic perovskite structure that is metastable at room temperature, can be stabilized by introducing a pseudo-halide ion like thiocyanate (SCN–) into its structure. The recent findings provide new insights into the stabilization of the α-phase via grain boundary and pseudo-halide engineering.
A material with good photophysical properties that has recently gained momentum is α-formamidinium lead iodide or α-FAPbI3 (where FA+ = CH(NH2)2+), a crystalline solid with a cubic perovskite structure. Solar cells made of α-FAPbI3 exhibit a remarkable 25.8% conversion efficiency and an energy gap of 1.48 eV. Unfortunately, α-FAPbI3 is metastable at room temperature and undergoes a phase transition to δ-FAPbI3 when triggered by water or light. The energy gap of δ-FAPbI3 is much larger than the ideal value for solar cell applications, making the preservation of the α-phase crucial for practical purposes. To overcome this problem, the team of researchers, led by Associate Professor Takafumi Yamamoto from Tokyo Institute of Technology (Tokyo Tech), has recently presented a new strategy for stabilizing α-FAPbI3.
According to reports, Panasonic is planning to sell windows made of “power-generating glass”, with perovskite solar cells integrated into transparent panes, to deliver power for homes. The module reportedly has a conversion efficacy of 17.9%, which is said to be the second highest worldwide for a perovskite cell larger than 800 sq. centimeters, ( after China’s UtmoLight - 18.6%).
Panasonic has been developing the cells since 2014 but only recently completed a test project, which consisted of installing the innovative glass on the balcony of a model home in its smart-town project in Kanagawa prefecture.
UNSW Sydney has received more than AUD$6 million (around USD$3,850,000) in the Australian Research Council (ARC) Discovery Early Career Research Awards (DECRA) round for 2024. Among the recipients are two perovskite-oriented projects.
The Australian Research Council (ARC) is supporting 200 new early career research projects with more than $86 million in funding for this 2024 round. Fourteen of the 200 projects have been awarded to early career researchers at UNSW.
Japanese electronics giant, Toshiba, has reportedly achieved a power conversion of 16.6% for a 703cm2 polymer film-based perovskite solar module.
Toshiba representatives were quoted saying that the Company has provided large film-based perovskite PV module as experimental materials for demonstrations, probably referring to a project conducted at the Aobadai station in Yokohama that includes analyzing indoor performance.
Researchers from Pennsylvania State University have developed a cost-effective method for creating bio-inspired solar devices that could improve the performance of perovskite solar technology. The team drew inspiration from cell membranes, the protective barriers around cells in all living organisms.
The researchers combined perovskite solar cell material with a synthesized version of natural lipid biomolecules to help protect against moisture-induced degradation. These biomolecules are fatty or waxy materials that don’t dissolve in water. The biomolecules formed a membrane-like layer around the perovskite, boosting stability and efficiency in tests. The approach could have a great impact on how perovskite solar cells are designed.
Researchers from the Netherlands' Eindhoven University of Technology, TNO, TNO/Holst Centre and Eindhoven Institute for Renewable Energy Systems (EIRES) have designed a monolithic perovskite-PERC tandem solar cell that utilizes a new type of tunnel recombination junction (TRJ) based on indium tin oxide (ITO), nickel(II) oxide (NiO), and carbazole (2PACz).
The scientists explained that TRJs are usually based on ITO and 2PACz alone, and that the addition of the NiO layer is intended to reduce electrical shunts in the perovskite top cell, due to the inhomogeneity of the 2PACz layer on ITO.
Researchers from The University of Sydney, University of New South Wales, Macquarie University and University of Technology Sydney have demonstrated efficient perovskite solar cells (PSCs) on steel substrates.
The team explained that steel, being flexible and conductive, can itself can act as both a substrate and an electrode for either large-area-monolithic-panel or smaller-area-singular single-junction or multi-junction cell fabrication. The reported cells could be used for building-integrated PV (BIPV), vehicle-integrated solar (VIPV), or other design-integrated photovoltaics for terrestrial or space applications.