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:
MBraun, a major mechanical and industrial engineering company and an affiliate of Germany’s Indus Holdings AG, plans to invest almost USD$750,000 (1 billion won) in a South Korean university as part of a deal to jointly conduct solar cell-related research and development projects. MBraun will also donate research equipment to Sungkyunkwan University and help it build facilities for the projects. With the investment, MBraun and Sungkyunkwan University’s Advanced Institute of Nano-Technology (SAINT) will establish an application lab at the research center in Suwon, Gyeonggi Province.
“Korea is the birthplace of technological innovation. That’s why we decided to donate research equipment to a Korean university,” Patrick Bieger, MBraun’s chief executive, said in a recent interview with The Korea Economic Daily in Seoul. He said it’s the first time that MBraun has decided to invest in a university, which shows how important the Korean market is in terms of technological innovations.
Scientists from the Centre for Solar Energy and Hydrogen Research Baden-Württemberg (ZSW) have achieved 21.1 percent efficiency with tandem perovskite - CIGS solar cells. These thin-film-based modules are highly efficient, light and flexible and can open doors to many new use cases for which standard rigid modules are not suitable.
ZSW’s tandem solar module has an area of nine square centimeters and achieves 21.1 percent efficiency. This prototype also features scalable component architecture suitable for industrial manufacturing. The best performance attained to date with tandem solar modules made of perovskite and CIGS is just slightly higher at 22 percent. ZSW has already achieved an excellent efficiency level of 26.6 percent with this combination of materials in smaller laboratory cells.
In June 2021, Tokyo Chemical Industry Company Limited (TCI) started offering new hole selective self-assembled monolayer (SAM) forming agents, 2PACz [Product Number: C3663], MeO-2PACz [D5798] and Me-4PACz [M3359] for high performance perovskite solar cells and OPVs. Now, TCI has expanded its range of SAMs by adding two new high-efficiency materials: Me-2PACz [M3477] and Br-2PACz [B6391].
The SAM materials enable efficient, versatile and stable p-i-n perovskite solar cell devices. These materials are useful for tandem solar cells as they grant conformal coverage on rough textures. In fact, a perovskite solar cell that uses the SAM hole transport layer can realize more than 20% efficiency without using dopants or additives. Perovskite-Silicon tandem solar cells that use Me-4PACz as a hole contact material realized 29.15% efficiency. Costs are lowered thanks to extremely low material consumption, and the processing is very simple and scalable.
Researchers from Northwestern University, University of Toronto and the University of Toledo have developed an all-perovskite tandem solar cell with extremely high efficiency and "record-setting" voltage.
“Further improvements in the efficiency of solar cells are crucial for the ongoing decarbonization of our economy,” says U of T Engineering Professor Ted Sargent (ECE). “While silicon solar cells have undergone impressive advances in recent years, there are inherent limitations to their efficiency and cost, arising from material properties. Perovskite technology can overcome these limitations, but until now, it had performed below its full potential. Our latest study identifies a key reason for this and points a way forward.”
French solar module manufacturer Voltec Solar and the Institut Photovoltaïque d’Île-de-France (IPVF) have announced plans to set up a factory for four-terminal (4T) tandem perovskite-silicon solar panels in France. The “France PV Industrie” project aims to build a gigafactory for solar panels, with a dual objective: to produce more efficient solar panels locally and to create a sustainable industry, based on a fast-growing market and a breakthrough technology.
The IPVF and Voltec plan to create a joint venture (France PV Industrie) so they can secure the necessary financing to scale up to industrial production. The pilot line will require an investment of €15 million ($15.4 million) and the industrial demonstrator €50 million. The partners estimate the total investment at around €1 billion by 2030. The facility will make modules based on IPVF's 4T tandem solar cell technology. The two entities plan to set up the first pilot production line by the end of 2023 and the first 200 MW industrial demonstrator in 2025. They will then increase the factory's capacity to 1 GW in 2027 and 5 GW by 2030.
Researchers from the Technical University of Dresden, led by Prof. Yana Vaynzof, have demonstrated a new concept for the formation of a heterojunction for photovoltaics. The team took advantage of the fact that materials can often exist in different structural configurations, termed crystalline phases. This phenomenon, called polymorphism, means that the same material can exhibit different properties, depending on the specific arrangements of atoms and molecules in its structure.
By interfacing two such phases of the same material, Prof Vaynzof and her team demonstrated for the first time the formation of a phase heterojunction solar cells. Specifically, the researchers chose a caesium lead iodide perovskite – a highly efficient solar cell absorber material – in the beta and gamma phases to realise their new concept.
It was recently reported that Contemporary Amperex Technology Limited (CATL), the Chinese manufacturer of energy devices, has filed to publicize its patents for the designs and manufacturing processes of several PV products.
The patents, which have been applied under the category of solar PV products, cover a backsheet, a transparent substrate, a perovskite PV cell, and a device design.
Researchers from the University of Surrey, Swansea University, University of Sheffield, University of Cambridge and University of Oxford in the UK, China-based CAS and Canada's University of Toronto have fabricated an inverted perovskite solar cell by using a surface modulator that reportedly facilitates superior passivation on perovskite surfaces, increasing overall cell efficiency. As the surface modulator, the scientists tested two organic halide salts known as 4-hydroxyphenethylammonium iodide (HO-PEAI), and 2-thiopheneethylammonium iodide (2-TEAI).
“These modulators can affect the surface energy of the perovskite films,” the team explained. They explained that the two compounds can dramatically reduce non-radiative interfacial recombination. This can have a significant impact on electrical performance in perovskite cells, with implications for open-circuit voltage, short-circuit current, fill factor, and ultimately, power conversion efficiency. They reported that “2-TEAI showed a stronger interaction than HO-PEAI, forming a quasi-2D structure on the perovskite surface without further annealing.”
Researchers from the National Center for Nanoscience and Technology (NCSNT) of the Chinese Academy of Sciences (CAS) and Beihang University have developed a sulfonium cations-assisted intermediate engineering strategy to study the evolution of intermediates and the film properties of quasi-2D perovskites. The researchers developed a facile strategy for intermediate engineering by employing sulfonium cations to regulate the transformation of intermediates during the crystallization process and improve the film quality of quasi-2D perovskites.
The intermediates were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) to reveal the composition and transformation process of the intermediates. The introduction of sulfonium cations inhibited the formation of unfavorable solvated lead iodide and promoted the formation of favorable perovskite intermediates with fiber-like morphology, which is conducive to the formation of high-quality perovskite crystals. The above effects have been confirmed in quasi-2D perovskite with different n values and 3D perovskites.
Scientists from the Ural Federal University (UrFU) and the Institute of Organic Synthesis of the Ural Branch of the Russian Academy of Sciences (along with their colleagues) have proposed a new type of material for transporting electrons in perovskite solar cells, which has a number of advantages.
The team reported that with the new material, they were able to achieve solar energy conversion efficiency of 12%. "The family of molecules we found carries electrons in PSCs slightly worse than the fullerenes used today, but they are about twice as cheap, much easier to produce, and have a number of other technological advantages," says Gennady Rusinov, associate professor at the Department of Organic Synthesis Technology of UrFU.