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).
What’s next?
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:
New project by Dutch-German consortium to develop simplified tandem solar modules for European market
TNO, in cooperation with Dutch and German industrial partners, is advancing a perovskite/silicon tandem solar module suitable for early market introduction.
FIT4Market, a four-year research project supported by the Netherlands Enterprise Agency (RVO), will help drive CO2 reduction through to 2030, supporting national climate objectives. It is also a step towards bringing PV production back to Europe and rebuilding a competitive PV supply chain.
UCLA and Midsummer develop perovskite-CIGS tandem solar cells with 24.9% efficiency
University of California, Los Angeles (UCLA) researchers have joined forces with Swedish building-integrated PV (BIPV) module manufacturer, Midsummer, on a project that has yielded a four-terminal (4T) tandem solar cell based on a top cell made of perovskite and a bottom cell relying on copper, indium, gallium and selenium (CIGS).
The joint project between Midsummer and Prof. Yang's lab at UCLA resulted in a four-terminal perovskite-CIGS tandem solar cell, based on a commercial CIGS solar cell, that reached 24.9 percent efficiency. The solar cell was based on a perovskite top cell that has been optimized for integration with Midsummer’s CIGS cells that are utilized in their commercial suite of BIPV products.
Researchers advance slot-die coated perovskite solar cells and ink properties
Scientists from Germany’s Helmholtz-Zentrum Berlin (HZB) and HTW Berlin have examined how precursor inks influence the quality of perovskite thin films. The best cells were scaled up to minimodule size. The team showed that when slot-die coating the halide perovskite layers on large areas, ribbing effects may occur but can be prevented by adjusting the precursor ink's rheological properties.
Prof. Dr. Eva Unger's team at Helmholtz-Zentrum Berlin has extensive expertise in solution-based processing methods and is investigating options for upscaling. "Perovskite photovoltaics is the best solution-processable PV technology available," says Eva Unger, "but we are only just beginning to understand how the complex interaction of the solvent components affects the quality of the perovskite layers."
Researchers demonstrate breakthrough roll-to-roll printable perovskite solar cell
A team of scientists at Swansea University has used a combination of a low-temperature device structure and roll-to-roll-compatible solution formulations to make a fully roll-to-roll (R2R) printable device architecture overcoming interlayer incompatibilities and recombination losses.
A sample of the new fully roll-to-roll (R2R) coated device. Credit: Swansea University (from Techxplore)
This means that using slot die coating in a R2R process, the team from the SPECIFIC Innovation and Knowledge Center at Swansea University has established a way to create "fully printable" perovskite photovoltaics.
CEA-INES and Enel Green Power reach 26.5% efficiency for tandem perovskite-silicon solar cell
Researchers at France's National Solar Energy Institute (INES) – a division of the French Alternative Energies and Atomic Energy Commission (CEA) – and Italian renewables specialist Enel Green Power have reportedly developed a two-terminal tandem perovskite-silicon solar cell with a power conversion efficiency of 26.5%.
The scientists said the new result improves on the 25.8% efficiency they achieved for the same kind of cell in December 2022. “The device with an active area of 9 cm² has an open-circuit voltage above 1,880 mV,” CEA-INES said, noting that the improvement on the device, which is based on a p-i-n configuration, was also due to “shading correction.” No additional technical details were disclosed.
Researchers develop strategy to reduce the formation of anions vacancy defects in halide perovskite solar cells
Researchers at China's Shaanxi Normal University and Chinese Academy of Sciences (CAS) have designed a novel strategy to reduce the formation of anions vacancy defects in halide perovskite solar cells. The team reported that the new approach results in higher efficiency and remarkable stability.
The new method, which they defined as 'a one-stone-for-two-birds' strategy, utilized a ligand known as 3-amidinopyridine (3AP) to pin anions in the device. Anions can control the nucleation and growth of the perovskite crystals and act as a passivating agent to improve the crystallinity, thus ensuring improved efficiency. The team says the 3AP molecules deposited on the perovskite layer are able to form strong chemical bonds with the cell's lead(II) iodide (Pb–I) interlayer and, as a consequence, create a sustainable pinning effect.
Ascent Solar Technologies repurposes its solar facility to advance perovskite solar commercialization
Ascent Solar Technologies, a U.S. manufacturer of lightweight, flexible and durable CIGS thin-film photovoltaic (PV) solutions, has announced that it has commissioned its Thornton manufacturing facility as a Perovskite Center of Excellence (COE). Effective immediately, the facility will be dedicated to the industrial commercialization of Ascent’s patent-pending perovskite solar technologies that are reportedly demonstrating lab efficiencies above 20%.
Ascent has dedicated its Thornton facility to the purpose of Perovskite manufacturing development, and to the conversion of the Company’s patent-pending Perovskite solar technology to industrial scale. The COE is resourced by a dedicated team of experts spanning Research, Development, Manufacturing and Operations; USD $30 million of industrial equipment at original cost; Ascent’s patent-pending Perovskites intellectual property; and operational facilities with 17 years of manufacturing heritage.
Researchers use Ruddlesden-Popper perovskites for improved solar cells
Scientists China's Zhengzhou University, Xi'an Jiaotong University and Chinese Academy of Sciences (CAS) have designed a solar cell based on low-dimensional Ruddlesden-Popper (LPDR) perovskite that is said to have improved carrier transport properties.
The team explained that the new cells are more stable compared to regular 3D perovskite solar cells and are suitable for building-integrated photovoltaics (BIPV), conventional solar, and wearable devices.
Researchers develop strategy to stabilize 3D/2D perovskites for better solar cells
Researchers at Huazhong University of Science and Technology, Wuhan University of Technology and University of Toronto recently introduced a new approach for fabricating more stable 3D/2D heterostructures, preventing their degradation. Their approach is based on the introduction of an additional layer between the structures; 3D and 2D perovskite layers.
2D and quasi-2D modified 3D perovskite heterostructures (i.e., structures comprised of 3D and 2D perovskite materials) have several advantageous qualities, such as enabling the passivation of defects and a favorable band alignment, which improve a perovskite solar cells' open-change voltage and fill factor. 3D/2D heterostructures are typically created by spin coating an organic cation salt solution on top of a 3D perovskite material and forming a thin 2D perovskite layer on its surface. This process, however, can facilitate the subsequent degradation of the heterostructures in some conditions, due to the diffusion of ions between the 2D perovskite surface and underlying bulk 3D perovskite.
EU's Project SUNREY targets sustainable and efficient perovskite solar cells with reduced lead content
Project SUNREY (”Boosting SUstaiNability, Reliability and EfficiencY of perovskite PV through novel materials and process engineering”) is a three-year project which started on November 1, 2022. It is coordinated by the Fraunhofer Institute for Applied Polymer Research IAP in Potsdam, Germany. The project aims to further the development of highly-efficient solar cells based on non-critical raw materials (with a focus on making perovskite solar cells more sustainable, efficient and durable) and to strengthen the innovation potential of the European industry.
SUNREY is funded by the European Union’s research and innovation program Horizon Europe within the framework of the Green Deal Initiative with 4.25 Million Euro.