EPFL

Researchers from Peking University, Tsinghua University, Beijing Institute of Technology and Ecole Polytechnique Fédérale de Lausanne (EPFL) have tackled a reproducibility challenge in black-phase formamidinium lead iodide (α-FAPbI₃) perovskites. They explained that while this is the desired phase for photovoltaic applications, water can trigger formation of photoinactive impurity phases such as δ-FAPbI₃. The team found that the classic solvent system for perovskite fabrication exacerbates this reproducibility issue. 

Growth of the photoactive black phase of formamidinium lead iodide (α-FAPbI₃) usually requires dimethyl sulfoxide solvent, but the hygroscopic nature of this chemical also promotes water-induced degradation to the photoinactive phase. the scientists showed that a larger chlorinated organic molecule can form a hydrophobic capping layer that enables perovskite crystallization under humid conditions by protecting growing crystallites from water. 

Researchers at EPFL, Shanghai University and Université catholique de Louvain recently developed a method based on machine-learning to quickly and accurately search large databases, leading to the discovery of 14 new materials for solar cells.

The research project, led by EPFL's Haiyuan Wang and Alfredo Pasquarello, developed a method that combines advanced computational techniques with machine-learning to search for optimal perovskite materials for photovoltaic applications. The approach could lead to more efficient and cheaper solar panels, transforming solar industry standards.

Researchers from EPFL, CSEM and Empa have demonstrated a cell design combining additive and substrate engineering that yields consistently high power conversion efficiencies and discussed various design aspects that are important for reproducibility and performance. 

The team presented two key developments with a synergetic effect that boost the PCEs of tandem devices with front-side flat Si wafers—the use of 2,3,4,5,6-pentafluorobenzylphosphonic acid (pFBPA) in the perovskite precursor ink that suppresses recombination near the perovskite/C60 interface and the use of SiO₂ nanoparticles under the perovskite film that suppress the enhanced number of pinholes and shunts introduced by pFBPA, while also allowing reliable use of Me-4PACz as a hole transport layer. 

Researchers from EPFL, Soochow University, Chinese Academy of Sciences, Lomonosov Moscow State University, Luxembourg Institute of Science and Technology (LIST), Julius Maximilian University of Würzburg, Toin University of Yokohama, Southern University of Science and Technology, Xi’an Jiaotong University, North China Electric Power University and Toyota Motor Europe recently developed a solar panel relying on EPFL's record-breaking 25.32%-efficient 2D/3D perovskite solar cells unveiled in July 2023.

The group's research demonstrates a larger surface area of 27.22 cm², achieving an impressive efficiency of 23.3%. In the paper, the scientists explain that the module's high efficiency was achieved thanks to a synergistic dopant-additive combination strategy aimed to improve the cell absorber's uniformity and crystallinity. They used, in particular, methylammonium chloride (MACl) as a dopant and a Lewis-basic ionic liquid known as 1,3-bis(cyanomethyl)imidazolium chloride ([Bcmim]Cl) as an additive.

An international group o researchers, including ones from the Fraunhofer Institute for Solar Energy Systems ISE, Solaronix, University of Cambridge, École Polytechnique Fédérale de Lausanne (EPFL) and others, have developed a method to re-manufacture fully encapsulated perovskite solar cells after recycling. According to the researchers, the re-manufactured devices can achieve 88% of their original efficiency.

The novel method for re-manufacturing perovskite solar cells (PSCs) uses carbon-based electrodes (CPSMs). Re- manufacturing, as opposed to merely recycling, is described as the combination of re-used, recycled, repaired, or replaced parts to make a new product. “In this work, we demonstrate for the first time a re-manufacturing strategy for glass-glass encapsulated perovskite solar cells,” the scientists stated. “Our study presents a facile experimental method to remove the edge-sealant, encapsulant, back electrode, and degraded perovskite, allowing reuse of the device constituents.”

Researchers at Korea's Pusan National University, Kyungpook National University, Switzerland's École Polytechnique Fédérale de Lausanne (EPFL) and University of Fribourg have pioneered an approach that not only rectifies lead leakage but also focuses on interfacial passivation. The team used the method to achieve perovskite solar cells with 21.7% power conversion energy.

The presence of lead ions in perovskite solar cells not only causes lead leakage, which is hazardous to the environment, but in the presence of moisture, the perovskite tends to degrade. Multiple approaches have been suggested to resolve this issue, including encapsulating the device and compositional engineering of the perovskite light absorbers. The crown ether was found to assist in resisting degradation due to moisture for 300 hours at room temperature and 85 percent humidity. In the study, the researchers tested many crown ethers, but found that B18C6 was the best for interfacial passivation.

The DIAMOND project aims at developing ultra-stable, highly-efficient and low-cost perovskite photovoltaics with minimized environmental impact, promising stabilities far beyond all previous achievements of photovoltaic solar cells.

It was launched in October 5^th, 2022, and is planned to continue until November 30^th, 2025. 

A research team, led by Northwestern scientists, has developed a method that could moves perovskite solar cells closer to industry adoption and widespread use. Using liquid crystals that can respond to temperature change and avoid accumulating precipitation, the group enabled the protection of large-area perovskite films. 

This approach led to a 22% efficiency and a stabilized efficiency of 21% for solar modules with enhanced damp heat (85% relative humidity at 85 degrees Celsius) stability and a size of 31 sq. centimeters.

The EU-funded P4SPACE project started in April 2023 and will run until the end of March 2025.

The project will develop and scale-up PSCs with high performance and durability in harsh space environments. It will aim to deliver sustainable PV technology for any present and future space environment application.

A collaborative team of researchers, including ones from Uppsala University, CNR-SCITEC, Fraunhofer ISE, University of Cambridge, Empa, EPFL and additional institutes, recently introduced an unexplored dimethylphenethylsulfonium iodide (DMPESI) molecule to post-treat formamidinium lead iodide perovskite films. The treated films showed outstanding stability upon light soaking and remarkably remains in black-phase after 2 years ageing under ambient condition without encapsulation. 

Fresh and 24-month aged unencapsulated perovskite film (1.0 cm by 2.0 cm) without and with DMPESI treatment of different concentrations. Image from Nature Energy

The DMPESI-treated PSCs deliver a breakthrough record in operational stability of highly-efficient PSCs with less than 1% performance loss after more than 4500 h at maximum power point tracking, yielding an extraordinarily high theoretical T80 of over 9 years under continuous 1-sun illumination, which would correspond to a photon flux of an outdoor PV installation in Sweden or Germany (1,000 kWh m−2 per year) of over 78 years.