Ligand exchange of SnO2 effectively improving the efficiency of flexible perovskite solar cells

Owing to the advantages of portability and flexibility, flexible perovskite solar cells have broad application prospects in the fields of portable wearable electronics and photovoltaic buildings. However, high temperature annealing process is often needed to improve the crystallinity and electron transport properties for electron transport layer, which restricts the development of flexible perovskite solar cells. In this work, well crystalline and monodisperse SnO2 nanocrystals are synthesized by facile solvothermal method with the assistance of oleic acid molecules. However, the presence of oleic acid molecules blocks the transportation of photogenerated electrons on account of the insulation of oleic acid molecules. To address the problem, the oleic acid ligands are ulteriorly peeled off by ligand exchange technique. Surprisingly, the resulted SnO2 electron transport layer exhibits superior electron extraction and transport capacity. The final power conversion efficiency comes to 17.96% from 13.71%. (C) 2021 Elsevier B.V. All rights reserved.