Ecole polytechnique fédérale de Lausanne (EPFL)

An international team of researchers, including ones from Iritaly Trading Company, École Polytechnique Fédérale de Lausanne (EPFL), University of Rome Tor Vergata, Argonne National Laboratory and Italy-based Greatcell Solar, has reported a co-crystal engineering approach to improve the long-term stability of perovskite solar cells and modules.

The team used a neutral molecule, benzoguanamine, as a linker in low-dimensional perovskites, replacing conventional ionic molecules, to form a co-crystal. By applying this co-crystal layer onto the perovskite layer, they achieved power conversion efficiency of 23.4% in small-area solar cells, and 23.1% and 18.5% on solar modules with active areas of 9.0 cm² and 48 cm², respectively. The solar modules retained more than 95% and 98% of their initial efficiency after >5,000 h of 1-sun light soaking and >1,000 h of ultraviolet-ray exposure, respectively, at maximum power point conditions. They also retained more than 91% of their initial efficiency after >5,000 h of continuous thermal stress at 85 °C.

Researchers from China's Southeast University, Henan University and Xiamen University, Germany's HZB, Switzerland's EPFL, Imperial College London, Queen Mary University of London, and Cardiff University in the UK and Italy's University of Cagliari have developed an interfacial engineering strategy that significantly enhances both the power conversion efficiency and operational stability of metal halide perovskite solar cells.

Metal halide perovskite photovoltaics exhibit outstanding optoelectronic properties, including high absorption coefficients and long carrier diffusion lengths, yet their long-term reliability remains a principal barrier to industrial deployment. To address this limitation, the international team introduced sodium heptafluorobutyrate (SHF) as a multifunctional interfacial modifier positioned between the perovskite absorber and the fullerene-based electron-selective contact (C60).

Researchers from EPFL, Northwestern University, University of Toronto, Kaunas University of Technology and Toin University of Yokohama recently achieved one of the highest efficiencies ever reported for fully inorganic perovskite solar cells. They also demonstrated for the first time that these cells can operate stably for hundreds of hours, approaching the reliability of commercial silicon solar cells.

Long-term stability is essential for commercialization of perovskite technology. One of the most important methods for reducing defects and protecting the surface from external factors is passivation. This process makes the perovskite surface more resistant to temperature, humidity, and other environmental conditions, thereby extending the device’s lifetime. “Passivation makes the perovskite surface chemically inactive, eliminating the defects introduced during production,” explains Dr. Kasparas Rakštys, from the Faculty of Chemistry at Kaunas University of Technology (KTU) in Lithuania.

Inverted perovskite solar cells (PSCs) can be limited by non-radiative recombination at both the perovskite absorber surface and the perovskite/charge transport layer interface. Researchers from École Polytechnique Fédérale de Lausanne (EPFL), King Abdullah University of Science and Technology (KAUST), Centre d’Electronique et de Microtechnique (CSEM), Potsdam University and IPVF have introduced a bimolecular passivation strategy that simultaneously addresses these two bottlenecks by combining phosphonic acids with piperazinium chloride. 

The phosphonic acids effectively passivate perovskite surface defects, such as lead-related traps, while piperazinium chloride improves the perovskite/electron transport layer interface by enhancing band alignment, introducing a favorable field effect, and homogenizing the surface potential. Together, these complementary effects increase the quasi-Fermi level splitting by approximately 100 mV, substantially improving voltage retention in devices.

An international team led by University College London (UCL) researchers has developed durable new solar cells capable of efficiently harvesting energy from indoor light, meaning devices such as keyboards, remote controls, alarms and sensors could someday be battery free.

The team, which also included scientists from Imperial College London, London South Bank University, EPFL, Phoenixolar and Ordos New Energy Research Institute, explained that despite well-matching indoor illumination spectra, the performance of wide bandgap perovskite solar cells (WB-PSCs) for indoor photovoltaics (i-PV) is hindered by photo-induced halide phase segregation and trap-assisted non-radiative recombination. In this recent work, the team designed a Triple Passivation Treatment (TPT) reassembly strategy to simultaneously suppress bulk and surface defects.