Stability

Canon has announced that it has developed a high-performance material which is expected to improve the durability and mass-production stability of perovskite solar cells (PSCs). The Company aims to initiate mass production in 2025.

Canon stated that several issues are currently standing in the way of PSC commercialization. For one, the crystal structure of the perovskite layer (photoelectric conversion layer) is susceptible to the effects of water, heat, oxygen, etc. in the atmosphere, which results in low durability. Furthermore, it is difficult to achieve stable mass production when manufacturing perovskite solar cells with a large surface area. It has been recognized that a structure covering the perovskite layer is needed to solve these problems. Therefore, Canon developed a special functional material to coat the perovskite layer by applying the material technology it cultivated through the development of photosensitive members, a key component of multifunction office devices and laser printers.

Researchers at Rice University, along with researchers from several institutions in the U.S. and abroad, including Lawrence Berkeley National Laboratory; University of California, San Diego; University of Lille, National Center for Scientific Research (CNRS), Centrale Lille Institut; University of Artois; Northwestern University; Purdue University; University of Rennes, INSA Rennes, CNRS, Institut FOTON; Brookhaven National Laboratory; University of Washington; and Northwestern University, have described a way to synthesize formamidinium lead iodide (FAPbI₃) ⎯ the type of crystal currently used to make the highest-efficiency perovskite solar cells ⎯ into ultrastable, high-quality photovoltaic films. The overall efficiency of the resulting FAPbI₃ solar cells decreased by less than 3% over more than 1,000 hours of operation at temperatures of 85 degrees Celsius (185 Fahrenheit).

“Right now, we think that this is state of the art in terms of stability,” said Rice engineer Aditya Mohite, whose lab has achieved various improvements in perovskites’ durability and performance over the past several years. “Perovskite solar cells have the potential to revolutionize energy production, but achieving long-duration stability has been a significant challenge.”

Researchers from Australia's Griffith University and Queensland University of Technology have reported the fabrication of planar carbon-based perovskite solar cells (c-PSCs) with high efficiency and excellent stability, by employing electrochemically produced large-area phosphorene flakes as a hole-transporting layer (HTL). 

Carbon-based perovskite solar cells have attracted increasing attention due to their many advantages, including: ease of fabrication, the potential of assembling flexible devices, low manufacturing costs and more. However, c-PSCs suffer from limited hole extraction and high charge carrier recombination due to inadequate interface contact between the carbon electrode and perovskite film.

MIT researchers have developed a new computer vision technique that significantly speeds up the characterization of newly synthesized electronic materials. The technique automatically analyzes images of printed semiconducting samples and quickly estimates two key electronic properties for each sample: band gap and stability.

Overview of the synthesis and characterization pipeline for perovskite semiconductors. Image credit: Nature Communications

The new technique reportedly characterizes electronic materials 85 times faster compared to the standard benchmark approach. The researchers intend to use the technique to speed up the search for promising solar cell materials. They also plan to incorporate the technique into a fully automated materials screening system.

Researchers at China's Hangzhou Dianzi University have modified the absorber of a conventional perovskite solar cell with potassium trifluoromethanesulfonate (KTFS) and found that the additive improved the device's performance and stability. The cell’s perovskite film reportedly showed less lead defects and lower J-V hysteresis.

“The KTFS molecule is a typical kind of potassium salt including the cationic potassium (K⁺) and anionic trifluoromethanesulfonate (SO3CF3−), indicating a bifunctional interaction between KTFS and perovskite,” the team explained. “The sulfonyl group can passivate the undercoordinated lead of the deep-level defect and thus inhibit the non-radiative recombination.”

Researchers from China's Southwest Petroleum University, Beijing Institute of Technology, Chongqing University, National Center for Nanoscience and Technology and Tongwei Solar have designed a perovskite solar cell with remarkable perovskite film quality through the 'self-disintegrating seed' strategy. The device achieved both an impressive fill factor values and remarkable stability.

The researchers, in fact, report what they say is one of the highest fill factor values ever achieved for a perovskite solar cell, by reducing its nonradiative recombination and residual stress through what they called a self-disintegrating seed strategy.

Researchers at China's Qingdao University of Science and Technology and Canada's University of Toronto have developed a thermal regulation strategy by incorporating carboranes into perovskites to improve the performance of inverted tin-lead perovskite tech for all-perovskite tandem solar cells. 

The Chinese-Canadian research group has designed a monolithic all-perovskite tandem solar cell that utilizes a top inverted perovskite PV device based on an absorber made with mixed tin-lead (Sn-Pb) perovskite via the newly developed thermal regulation strategy.

Small-molecule ionic liquids are frequently used as efficient bulk phase modifiers for perovskite materials. However, their inherent characteristics, such as high volatility and ion migration, pose challenges in addressing the stability issues associated with perovskite solar cells (PSCs). Recently, researchers at China's Northwestern Polytechnical University and CNPC Tubular Goods Research Institute designed improved poly ionic liquids (ILs) with multiple active sites as efficient additives for perovskite materials.

The team's recent work shows how additive engineering with a polymerized ionic liquid to the metal halide perovskite material can improve the solar cell's function, helping to pave the way for the adoption of perovskite solar cells.

Researchers from Soochow University, Hunan University and Friedrich-Alexander University Erlangen-Nürnberg have incorporated pseudo-halogen thiocyanate (SCN) ions in iodide/bromide mixed halide perovskites and showed that they enhance crystallization and reduce grain boundaries. 

While perovskite/organic tandem solar cells could theoretically achieve high efficiency and stability, their performance is hindered by a process known as phase segregation, which degrades the performance of wide-bandgap perovskite cells and adversely affects recombination processes at the tandem solar cells' interconnecting layer. The team devised a strategy to suppress phase segregation in wide-bandgap perovskites, thus boosting the performance and stability of perovskite/organic tandem cells. This strategy entails the use of a pseudo-triple-halide alloy incorporated in mixed halide perovskites based on iodine and bromine.

Researchers at Austria's Johannes Kepler University Linz have developed lightweight, thin (<2.5 μm), flexible and transparent-conductive-oxide-free quasi-two-dimensional perovskite solar cells by incorporating alpha-methylbenzyl ammonium iodide into the photoactive perovskite layer. 

The team fabricated the devices directly on an ultrathin polymer foil coated with an alumina barrier layer to ensure environmental and mechanical stability without compromising weight and flexibility.