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Improvements to perovskite solar cells (PSCs) have focused on increasing their power conversion efficiency (PCE) and operational stability and maintaining high performance upon scale-up to module sizes. We report that replacing the commonly used mesoporous–titanium dioxide electron transport layer (ETL) with a thin layer of polyacrylic acid–stabilized tin(IV) oxide quantum dots (paa-QD-SnO 2 ) on the compact–titanium dioxide enhanced light capture and largely suppressed nonradiative recombination at the ETL–perovskite interface. The use of paa-QD-SnO 2 as electron-selective contact enabled PSCs (0.08 square centimeters) with a PCE of 25.7% (certified 25.4%) and high operational stability and facilitated the scale-up of the PSCs to larger areas. PCEs of 23.3, 21.7, and 20.6% were achieved for PSCs with active areas of 1, 20, and 64 square centimeters, respectively.

Moving a perovskite into the black The bandgap of the black α-phase FAPbI 3 (where FA is formamidinium) is nearly ideal for solar cells, but it is unstable with respect to the photoinactive yellow δ-phase. Lu et al. found that a film of the yellow phase was converted to a highly crystalline black phase by vapor exposure to methylammonium thiocyanate at 100°C, and it retained this structure after 500 hours at 85°C. Solar cells fabricated with this material had a power conversion efficiency of more than 23%. After 500 hours under maximum power tracking and a period of dark recovery, 94% of the original efficiency was retained. Science , this issue p. eabb8985