Inkjet-printed Ce-doped SnOx electron transport layer for improved performance of planar perovskite solar cells

Planar perovskite solar cells (PSCs) based on low-temperature solution-processed SnO2 electron transport layers (ETLs) usually suffer from energy losses within SnO2 ETLs or at SnO2/perovskite interfaces. Doping is an effective strategy to modify the properties of SnO2 and reduce such energy losses. Herein, Ce ions are incorporated into solution-processed SnOx and Ce-doped SnOx ETLs are fabricated for planar PSCs via inkjet printing. The Ce-doped SnOx ETL shows enhanced conductivity and improved energy level alignment with the perovskite layer, which can facilitate charge extraction and transport capabilities. Ce doping also effectively passivates the surface defects of SnOx. The photoluminescence characterization reveals that the carrier recombination is suppressed within the perovskite film. As a result, an improved power conversion efficiency (PCE) of 15.77% is obtained for the planar PSC with a Ce-doped SnOx ETL, compared to that of 14.66% for the undoped device. Furthermore, this work demonstrates a sustainable fabrication method which has great potential for the upscaling of PSCs.