January 2022

Researchers from KAUST and the University of Bologna have examined the root causes of harmful top-contact delamination in p-i-n perovskite/silicon tandem solar cells. Their findings aim to improve the stability of tandem modules, and prompt a search for new interfacial linking strategies to enable mechanically strong perovskite-based solar cells, as required for commercialization.

In their work, by combining macroscopic and microscopic analyses, the team identified the interface between the fullerene electron transport layer and the tin oxide buffer layer at the origin of such delamination. Specifically, they found that the perovskite morphology and its roughness play a significant role in the microscopic adhesion of the top layers, as well as the film processing conditions, particularly the deposition temperature and the sputtering power.

An international team of researchers from EPFL, North Carolina State University, Centre for Hybrid and Organic Solar Energy (CHOSE) at the University of Rome Tor Vergata and Uppsala University has demonstrated a technique for producing perovskite photovoltaic materials on an industrial scale, which could reduce the cost and improve the performance of mass-produced perovskite solar cells. The technique is low-cost, simple and energy-efficient.

'In the lab, researchers produce perovskite photovoltaic materials using a technique called spin coating, which creates a thin film of perovskite on a substrate ' but only on a small scale,' says Aram Amassian, co-corresponding author of a paper on the work and a professor of materials science and engineering at North Carolina State University.

A research group at FAU and the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN) have worked on a design aimed at significantly increasing the operational stability and life span of perovskite solar cells. Their design is based on a bilayer of polymers that protects the perovskites from corrosion at the same time as allowing uninterrupted charge transfer.

Until now, despite perovskite solar cells' potential, two major disadvantages have become apparent. Firstly, they do not have a particularly long life span, as perovskites tend to corrode on their interfaces and their performance capacity sinks rapidly, sometimes within days. Secondly, perovskite modules are not particularly robust in elevated temperatures, which severely limits their stability in practical use scenarios. This is mainly down to the layers doped with ions that are required for transporting the charge carriers but that can also lead to undesired secondary reactions.

Mitsubishi Materials Corporation has announced its participation in the Green Innovation Fund Project/Development of Next-Generation Solar Cells by the New Energy and Industrial Technology Development Organization (NEDO), as a company commissioned by EneCoat Technologies, which it finances through the MMC Innovation Investment Limited Partnership.

EneCoat Technologies, a startup originating from Kyoto University, is working on the development of perovskite solar cells and is attempting to replace the lead contained in perovskite solar cells with an alternative material. Mitsubishi Materials Corporation financed EneCoat Technologies and is examining collaboration with Enecoat regarding technologies that will contribute to improving the durability of perovskite solar cells and development of the peripheral materials required for eliminating lead.

Researchers from the Okinawa Institute of Science and Technology Graduate University (OIST) have developed blue LEDs based on metal halide perovskites, that, for the first time, uses asymmetrical bridges to hold the layers of perovskite together, creating a more stable structure.

'Perovskites have the potential to be a real game-changer in the lighting industry,' said first author Dr. Yuqiang Liu, a former post-doctoral researcher in the OIST Energy Materials and Surface Sciences Unit and currently a professor at Qingdao University, China. 'In only a few short years, the efficiency of perovskite LEDs ' how well they can transfer electrical energy into light energy ' has shot up to a level that rivals traditional LEDs, and soon will surpass them.'

Researchers from Tor Vergata University and University of Zanjan have developed a new method that uses a simple sheet of paper to deposit the perovskite films without any expensive equipment. The way to achieve high performance with this low-cost method is to soak the paper applicator in anti-solvent which almost doubles efficiencies compared to when using it dry, reaching 11% on flexible plastic substrates. Paper, compared to other soft applicators, possesses the right porosity and smoothness for deposition of high quality perovskite films.

Most perovskite films in laboratories around the world are deposited through spin coating which guarantees high control of film thickness as well as morphology. However, most of the ink is expelled during deposition and is wasted. There have been efforts to develop coating techniques for deposition over large areas. The most efficient solar cells fabricated via spin coating involve adding drops of anti-solvent (i.e., a liquid with differing properties to those used in the perovskite precursor inks) during spinning which improves the morphological quality of the perovskite semiconductor films. This method is very difficult to implement when employing large area coating techniques, however, where the careful engineering of the drying processes involve heaters or gas flows to control the morphology of the perovskite film.

A team of researchers from the National University of Singapore (NUS), the University of Hong Kong and Southern University of Science and Technology has reportedly "set a new record in the power conversion efficiency of solar cells made using perovskite and organic materials".

'The main motivation of this study is to improve the power conversion efficiency of perovskite/organic tandem solar cells. In our latest work, we have demonstrated a power conversion efficiency of 23.6% - this is the best performance for this type of solar cells to date,' said Dr. Chen Wei, Research Fellow at the NUS Department of Chemical and Biomolecular Engineering and the first author of this work.

Researchers at EPFL, Zurich University of Applied Sciences, Ulsan National Institute of Science and Technology, University of Ulsan and Uppsala University have designed an innovative way to increase the performance of perovskite solar cells and maintain it at a high level even at large scales. The new approach replaces the electron-transport layer with a thin layer of quantum dots.

With this new approach, the team, led by Professor Michael Grätzel at EPFL and Dr Dong Suk Kim at the Korea Institute of Energy Research, addressed one of the major obstacles facing the commercialization of perovskite solar cells - the fact that their power-conversion efficiency and operational stability drop as they scale up, making it a challenge to maintain high performance in a complete solar cell.

Researchers from Professor Tan Hairen group at Nanjing University in China recently developed all-perovskite tandem solar cells with a conversion efficiency of 26.4%, certified by JET.

The team developed ammonium-cation-passivated Pb-Sn perovskites with long diffusion lengths, enabling subcells with an absorber thickness of ~1.2 μm. Molecular dynamics simulations suggest that widely-used phenethylammonium (PEA) cations are only partially adsorbed on the surface defective sites at perovskite crystallization temperatures. The passivator adsorption is predicted to be enhanced using 4-trifluoromethyl-phenylammonium (CF3-PA), which exhibits a stronger perovskite surface-passivator interaction than does PEA.

Display market research firm DSCC says that perovskite-based QD films for LCD display applications could enter the market in 2022. DSCC says that perovskite materials could increase efficiency and color gamut compared to current solutions.

Last year we reported that Zhijing Nanoech has concluded a successful pilot with TCL, which has produced 500 75-inch QD-enhanced LCD TVs with Zhijing's PQDF films. The company hopes to achieve a design win with TCL for mass production.