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:
China's Three Gorges Group has announced that "the world's first commercial megawatt-level perovskite ground-mounted photovoltaic project was successfully connected to the grid on November 29".
The project is located in the Kubuqi Desert hinterland of Hangjin Banner, Ordos City, Inner Mongolia, and is supported by the Kubuqi 2 million kilowatt photovoltaic desert control project in the west of Inner Mongolia. The project has an installed capacity of 1 megawatt, covers an area of 40 acres, and utilizes a total of 11,200 modules of perovskite photovoltaic modules, as was reported.
Hanwha Qcells recently announced it will be closing its 3.5GW module factory in South Korea, in response to the stagnant solar market in the country. It was reported that the total installed capacity of solar power in South Korea has been continuously decreasing over the past three years, from 4.7GW in 2020 to 3.4GW in 2022, and is expected to further decrease in 2023.
Closing the factory comes as part of a plan to optimize Hanwha's photovoltaic module production capacity. However, Hanwha stated that it will continue to invest in its factory in Jincheon, South Korea, which will continue to produce TOPCon products and operate a perovskite tandem cell pilot line.
Researchers at South Korea’s Chonnam National University have reported perovskite-organic hybrid tandem solar cells with 23.07% efficiency processed entirely in open air, bringing the technology a step closer to economic viability.
Schematic illustration of the synthesis of all-inorganic perovskite thin films by dynamic hot-air-assisted method. Image from Energy & Environmental Science
Researchers have largely relied on meticulously engineering the perovskite crystal structure itself for greater resilience. But these delicate handling steps add cost and complexity not suitable for mass production. The team explained that the focus has recently shifted toward all-solution processed solar cells due to their low energy consumption fabrication processes. The team’s innovation, a dynamic hot air deposition technique, simplified the production process by eliminating the need for humidity-controlled environments.
Researchers at Germany’s Fraunhofer ISE have estimated that the practical power conversion efficiency potential of perovskite-silicon tandem solar cells may reach up to 39.5%. In a recent study, the Fraunhofer ISE scientists set out to provide guidelines for future research on perovskite-silicon tandem solar cells by identifying the most significant loss mechanisms at the perovskite/ETL interface, in the series resistance, and in light management.
The team explained that the calculated practical efficiency potential of 39.5% for a perovskite silicon tandem device under standard measurement conditions (STC) can serve as an input for future studies which are required for a better understanding of the full system before the commercialization of tandem solar cell technology can take place.
It was reported that China-based Ideal Deposition Equipment, a technology and equipment company with chemical vapor deposition technology as its core, has entered into a supply agreement with a top American photovoltaic company for manufacturing perovskite cells.
Ideal Deposition primarily focuses on producing equipment for PERC and TOPCon production. In recent years, it has launched a series of related equipment for mainstream photovoltaic cell producers worldwide. Additionally, it manufactures coating equipment for tandem layers of perovskite cells.
China-based BOE Technology Group (BOE), one of the leading companies in the global display technology field, recently launched a project to enter the photovoltaic industry by investing in perovskite solar cells. BOE held a ceremony to launch the project
It is believed that BOE's entry into the perovskite solar cell market will bring new energy to the industry, which is in line with the country's renewable energy policy. The Company has a strong R&D team and extensive experience in display technologies, which could be applied to the development of perovskite solar cells. BOE has also established partnerships with top universities and research institutions to promote the development of perovskite solar cells.
Researchers from the Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM), Germany's University of Potsdam and The Chinese University of Hong Kong have addressed an important aspect in the field of perovskite solar cells (PSCs) – the exact role of excess lead iodide content within the perovskite layer. While an optimal amount of excess lead iodide contributes to improved grain boundary passivation and blocking of minority charge carriers, leading to the development of highly efficient PSCs, the photo-stability of PSCs with surplus lead iodide remains a major concern. This concern stems from the catalytic role excess lead iodide can play in the degradation of PSCs under illumination.
The issue often arises during the fabrication of perovskite films using a two-step spin coating method, where the conversion of lead iodide films to perovskite is hindered due to challenges in controlling the reaction between lead iodide films and cationic precursor solutions. Various modifications of the two-step approach are presented in the literature, each aiming to achieve a near full conversion of lead iodide films into perovskite when exposed to cationic precursor solutions.
GCL Photoelectric Materials (GCL Perovskite), a subsidiary of GCL Tech, has announced that it was able to attain a photoelectric conversion efficiency of 18.04% on a perovskite single-junction solar module, with dimensions measuring 1,000mm by 2,000mm. It was reported that this result was officially tested and confirmed by the China National Institute of Metrology.
GCL Perovskite team has been working on achieving this objective of exceeding the anticipated conversion efficiency of 18% for standard-sized perovskite modules, and the team will now focus on conducting research and development for the next-generation perovskite tandem modules.
According to recent reports, China-based Xi'an Tianjiao New Energy has obtained nearly 100 million yuan (over USD$14,100,00) in angel round financing, led by Winreal Investment. The funds will primarily be used for building a perovskite pilot production line with a capacity of 10MW alongside other operational expenses covering consumables and staff.
Tianjiao, a perovskite solar cell developer, specializes in manufacturing single-cell perovskite modules including both flexible and rigid types. The rigid modules find their use primarily in PVBI, whereas the flexible ones are mounted on car roofs or used in 5G base stations.
French PV module manufacturer Voltec Solar has secured €9.3 million ($10.1 million) from Ademe, France’s environmental agency. The company plans to use the funds to accelerate the production of perovskite-silicon tandem solar panels.
The French manufacturer currently operates two 250 MW production lines at its factory in Dinsheim-sur-Bruche, France.