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

Abstract

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 SnO_x and Ce-doped SnO_x ETLs are fabricated for planar PSCs via inkjet printing. The Ce-doped SnO_x 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 SnO_x. 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 SnO_x 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.