A layered approach improves solar cells: Perovskite films received a boost in photovoltaic efficiency through controlled formation of charge-generating films and improved current transfer to the electrodes. Zhou et al. lowered the defect density of the film by controlling humidity while the perovskite film formed from lead chloride and methylammonium iodide. Low-temperature processing steps allowed the use of materials that draw current out of the perovskite layer more efficiently. These and other modifications enabled a maximum cell efficiency of just over 19% and an average of 16.6%. Science , this issue p. 542

SummaryThe dawn of a new era in optoelectronic technologies has emerged with the recent development of the organic–inorganic hybrid halide perovskite. Its exceptional attributes, including high carrier mobility, an adjustable spectral absorption range, long diffusion lengths, and the simplicity and affordability of fabrication render it one of the most exceptional and market-competitive optoelectronic materials for applications in photovoltaics, light emitting diodes (LED), photodetectors, lasers, and more. Moreover, its versatility in device architecture and ability to achieve relatively high performance devices via various processing techniques makes perovskites a highly promising material for various practical applications. Here, we review the organic–inorganic hybrid halide perovskite and delve into its recent progress and relevant applications

Moisture is assumed to be detrimental to organometal trihalide perovskite, as excess water can damage the crystallinity of the perovskite structure. Here, we report a growth mode for via thermal annealing of the perovskite precursor film in a humid environment (e.g., ambient air) to greatly improve the film quality, grain size, carrier mobility, and lifetime. Our method produces devices with maximum power conversion efficiency of 17.1% and a fill factor of 80%, revealing a promising route to achieve high quality perovskite polycrystalline films with superior optoelectronic properties that can pave the way towards efficient photovoltaic conversion.