Efficient flexible perovskite solar cells and modules using a stable SnO_(2)-nanocrystal isopropanol dispersion

The outstanding advantages of lightweight and flexibility enable flexible perovskite solar cells(PSCs)to have great application potential in mobile energy devices.Due to the low cost,low-temperature processibility,and high electron mobility,SnO_(2) nanocrystals have been widely employed as the electron transport layer in flexible PSCs.To prepare high-quality SnO_(2) layers,a monodispersed nanocrystal solution is normally used.However,the SnO_(2) nanocrystals can easily aggregate,especially after long periods of storage.Herein,we develop a green and cost-effective strategy for the synthesis of high-quality SnO_(2) nanocrystals at low temperatures by introducing small molecules of glycerol,obtaining a stable and well-dispersed SnO_(2)-nanocrystal isopropanol dispersion successfully.Due to the enhanced dispersity and super wettability of this alcohol-based SnO_(2)-nanocrystal solution,large-area smooth and dense SnO_(2) films are easily deposited on the plastic conductive substrate.Furthermore,this contributes to effective charge transfer and suppressed non-radiative recombination at the interface between the SnO_(2) and perovskite layers.As a result,a greatly enhanced power conversion efficiency(PCE)of 21.8%from 19.2%is achieved for small-area flexible PSCs.A large-area 5 cm×5 cm flexible perovskite solar mini-module with a champion PCE of 16.5%and good stability is also demonstrated via this glycerol-modified SnO_(2)-nanocrystal isopropanol dispersion approach.