Chlorine capped SnO2 quantum-dots modified TiO2 electron selective layer to enhance the performance of planar perovskite solar cells.

SnO2 quantum dots (QDs) ended with chlorine ions are introduced at the interface of spin-coated TiO2 electron selective layer (ESL)/perovskite to fill the pinholes in the layer and passivate the trapping defects. As a result of the increased interface electron collection and reduced bulk recombination, the planar perovskite solar cell with the QDs modified ESL gives the large power conversion efficiency enhancement from 14.9% to 17.3% and greatly improved stability under the continuous light irradiation.