Reducing the Voc Loss of Hole Transport Layer-Free Carbon-Based Perovskite Solar Cells via Dual Interfacial Passivation

Li 2 CO 3 is used to modify conformal SnO 2 as electron transport layer for hole transport layer-free carbon-based perovskite solar cells (C-PSCs). CO 3 2− can induce MA release from the perovskite layer, resulting in PbI 2 at the grain boundary of top interface of perovskite film which can passivate the grain boundary and the top surface defects. The Li 2 CO 3 -modified C-PSC exhibits a high power conversion efficiency (PCE) of 19.1%, with a V oc of 1.142 V. A record-high PCE of 33.2% is obtained under weak light-emitting diode illumination (2000 lx, 3000 K).