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Organic-inorganic perovskite solar cells (PSCs) are promising candidates for next-generation, inexpensive solar panels due to their high power conversion efficiency, which is on par with their commercial silicon counterparts. However, PSCs suffer from poor stability. A new subset of PSCs, quasi-two-dimensional Ruddlesden-Popper PSCs (quasi-2D RP PSCs), is known for improved photostability and superior resilience to environmental conditions in comparison with three-dimensional (3D) metal-halide PSCs. To expedite the search of new quasi-2D RP PSCs we report a combinatorial, machine learning (ML) enhanced high-throughput perovskite film fabrication and optimization study. We designed a bespoke experiment strategy and produced perovskite films with a range of different compositions through a fully automated drop-casting process. The performance and characterization data of these solar cells were used to train a ML model that allowed for material parameter optimization and directed the design of improved materials. The ML optimized quasi-2D RP perovskite films yielded solar cells with power conversion efficiencies reaching 16.3%.

This review focuses on the advancements in stability of perovskite solar cells under stress from ambient moisture, high temperatures, and UV light exposure. Moisture stability has been improved by utilizing several polymeric encapsulation methods, moisture-resistant hole transport layers (HTLs), CF4 plasma treatments, and perovskite grain crosslinking. Fluorinated encapsulation methods have proven especially successful, producing cells that maintained their PCE after 75 days at 50% RH and 5 mW cm−2 of UV radiation. Temperature destabilization has been hypothesized to occur as a result of perovskite phase transitions and the HTL dopant migration to the mesoporous TiO2 surface. Temperature-sensitive perovskites have been stabilized by tuning the Goldschmidt tolerance factor and introducing thermally resistant HTLs embedded in a polymeric matrix with polycarbonate acting as an effective thermal insulating matrix. UV light instabilities have also been shown to occur due to the photocatalysis of TiO2 and the TiO2 perovskite interface. The introduction of a Sb2S3 buffer or CsBr clusters as interface modifiers can stabilize the interface of TiO2 perovskite. Herein, we aim at highlighting the main processes that prevent perovskite degradation using polymers and interfacial modifiers.

Organic-inorganic halide perovskites have been identified as favorable candidates for the next generation of photovoltaics. Adding alkali metal halides to perovskite films has been shown to be a viable option to improve the perovskite film quality and to modulate their fundamental properties. In this work, we perform optical and electron-beam based characterizations of mixed Sn/Pb based perovskite films to investigate the effect of the addition of the alkaline metal halide SrI2. By analyzing structural (X-ray diffraction), morphological (Scanning Electron Microscopy), optical (photoluminescence), and chemical properties (X-ray photoelectron spectroscopy), we show a complex interplay of effects upon addition of Sr2+ into the perovskite solution. Low concentrations of Sr2+ increases lattice strain, which hints at incorporation of the additive into the perovskite lattice and improves the film optoelectronic properties. As the additive concentration increases beyond 0.5 mol %, microstrain decreases. At concentrations >0.5 mol %, Sr2+ induces significant reduction of the average domain size, which impacts both structural and optical properties of the perovskite film.