Flexibility

Scientists at the Chinese Academy of Sciences (CAS), Xuancheng Kaisheng New Energy Technology Company and Tianjin Institute of Power Sources have found a way to make flexible tandem solar cells more efficient and durable by enhancing the adhesion of top layers to the bottom layers of the cell.

Copper indium gallium selenide (CIGS) is a commercial semiconductor known for its outstanding adjustable bandgap, strong light absorption, low-temperature sensitivity, and superior operational stability, making it a promising candidate for bottom-cell use in next-generation tandem solar cells. Flexible perovskite/CIGS tandem solar cells combine a top layer of perovskite with a bottom layer of CIGS. This tandem cell holds great potential for lightweight, high-efficiency applications in the photovoltaic field but the rough surface of CIGS makes it difficult to produce high-quality perovskite top cells on top, which limits the commercial prospects of these tandem cells.

Researchers at the Korea Institute of Energy Research, Gyeongsang National University, University of Science and Technology (UST), Korea Institute of Science and Technology (KIST), Korea Institute of Energy Technology (KENTECH) and Yonsei University have developed lightweight flexible perovskite/CIGS tandem solar cells and achieved a power conversion efficiency of 23.64%, which they claim is the highest efficiency achieved in flexible perovskite/CIGS tandem solar cells to date. 

Image from: Joule

The solar cells developed by the research team are extremely lightweight and can be attached to curved surfaces, making it a promising candidate for future applications in buildings, vehicles, aircraft, and more.

Perovskite solar module manufacturer Mellow Energy has announced a new record for its integrated flexible perovskite solar module. Certified by the National Institute of Metrology of China, the module achieved an output power of 86.90 W and an efficiency of 17.38% over an area of 0.5 m². The test results showed no hysteresis in forward and reverse scans, and the MPPT test exhibited almost no degradation over 300 seconds.

Mellow Energy claims this to be the highest certified efficiency for a large-area flexible perovskite module known to date. The company further highlighted that the module is produced using an integrated molding process, eliminating the need for splicing, which results in better aesthetics and high reliability.

Researchers from China's Northwestern Polytechnical University, Chinese Academy of Sciences (CAS) and Henan University have addressed the stability challenge of flexible perovskite solar cells (FPSCs). Inspired by the exceptional wet adhesion of marine mussels via adhesive proteins (dopamine, DOPA), the scientists proposed a multidentate-cross-linking strategy, which combines multibranched structure and adequate dopamine anchor sites in three-dimensional hyperbranched polymer to directly chelate perovskite materials in multiple directions.

Schematics of key components for the underwater adhesion feature of marine mussels and HPDA adhesive in perovskite films and interfaces. Image from: Nature Communications

This constructs a vertical scaffold across the bulk of perovskite films from the bottom to the top interfaces, that intimately binds to the perovskite grains and substrates with a strong adhesion ability, and enhances mechanical durability under high humidity. 

Recently, a University of Louisville team of researchers used nanoparticle inks by Sofab Inks (a U of Louisville spinout) to create PSCs with ~20% PCE on flexible substrates. Their study addresses the solvent scope and perovskite compatibility of acetate-stabilized yttrium-doped SnO₂ (Y:SnO₂) dispersions.

Tin oxide (SnO₂) stands out as a compelling electron transport material (ETM) for perovskite solar cells (PSCs), boasting exceptional optoelectronic properties, coupled with low-temperature solution processability, cost-effectiveness, and remarkable stability. However, the widespread application of SnO₂ has been hindered by solvent incompatibilities, limiting its use to devices where it is deposited beneath the perovskite layer. To unlock the full potential of SnO₂ and expand its use across various device structures, including inverted PSCs and tandem devices, innovative deposition strategies will need to be developed. These advancements could pave the way for more efficient and versatile solar cell designs, pushing the field of photovoltaics forward.

The scientists showed that dispersions in several lower alcohols and select polar aprotic solvents can be directly deposited on perovskite using scalable and low-temperature processes. In addition, they are compatible with various perovskite formulations, including those with mixed cations and mixed anions.

India-based P3C has announced a partnership with the National Institute of Solar Energy (NISE). 

P3C and NISE have signed a Memorandum of Understanding (MoU) to accelerate India’s transition to a low-carbon, sustainable future. This partnership will focus on advancing perovskite solar technology and powering next-generation solar solutions, including glass and flexible perovskite modules, tandem solar cells, and advanced PV innovations for both urban and rural environments. The two parties' shared goal is to make clean energy accessible, efficient, and scalable across India, from rooftops and farmlands to smart cities and remote villages.

Researchers from Japan's Ritsumeikan University and Sekisui Chemical have studied the role of barrier films in shielding flexible perovskite solar modules from harsh environmental conditions. 

The research team utilized PSC modules made of methylammonium lead iodide (MAPbI₃), which were encapsulated with polyethylene terephthalate substrate with barrier films of varying water vapor transmission rates (WVTR). The PSC modules were subjected to a damp heat test, which utilized exposure of the modules to 85 °C temperature and 85% relative humidity. The conditions were set to simulate real-world outdoor conditions over extended periods.

EneCoat Technologies has announced a conversion efficiency of over 30% with a 4-terminal tandem cell consisting of stacked perovskite and crystalline silicon solar cells in a joint development project with Toyota Motor Corporation. 

This achievement underscores the profound research and development capabilities of both companies in the field of perovskite solar cells and accelerates the practical application of high-efficiency solar cells, which is the objective of the joint development project. In this project, the two companies focused on the transmittance of perovskite solar cells and succeeded in improving the infrared transmittance to 81%.

Japan-based startup PXP Corporation, developer of lightweight and flexible solar cells, has raised a total of 1.5 billion yen (almost USD$10 million) in Series A funding, led by SoftBank Corp., with participation from SOLABLE Corporation, Kowa Optronics Co., Ltd., Toyota Tsusho Corporation, J&TC Frontier LLC (a joint investment vehicle between JFE Engineering Corporation and Tokyo Century Corporation), Automobile Fund Co., Ltd., Mitsubishi HC Capital Co., Ltd., Yokohama Capital Co., Ltd., and TARO Ventures. SoftBank has invested approximately 1 billion yen and acquired approximately 29.9% of PXP's shares.

The solar cell technology being developed by PXP has a tandem structure that combines perovskite solar cells and chalcopyrite solar cells, said to achieve more than 1.5 times the energy conversion efficiency (theoretical value: about 42%) of conventional solar cells. In addition, it is lightweight and flexible, weighing about one-tenth of conventional solar cells, and has high durability against shock and vibration. It can be installed in various locations depending on the application, and it is expected to reduce installation costs. PXP and SoftBank aim to use PXP's next-generation solar cells for various purposes, such as operating SoftBank's data center with green energy, in anticipation of future electricity demand.

It was reported that Japan's Ministry of Economy, Trade and Industry (METI) and the New Energy and Industrial Technology Development Organization (NEDO) have decided to support a demonstration project for perovskite solar cells conducted by Sekisui Chemical and Tokyo Electric Power Company Holdings (HD). 

The total project cost is estimated at about 18.3 billion yen ( just under USD$119,000,000), with approximately 12.5 billion yen (around USD$81 million) to be subsidized through the Green Innovation (GI) Fund project. The project will verify installation methods, construction methods, and mass production technologies that take advantage of the unique characteristics of perovskite solar cells.