A low temperature processable tin oxide interlayer via amine-modification for efficient and stable organic solar cells

Abstract The exploitation of proper electron transport layers (ETLs) and interface optimization can play a pivotal role to promote the performance of organic solar cells (OSCs). In this work, low temperature processable tin oxide (SnO2) colloidal nanoparticles with ethanolamine (EA) treatment are successfully employed for efficient and stable OSCs with light soaking free. The EA is chemically bonded with SnO2, and the ethanolamine treated tin oxide (E-SnO2) layer delivers a suitable work function of 4.10 eV and a unique surface texture with suspended polar moieties. The enhanced performance of E-SnO2 based OSCs can be attributed to the improved charge transport and electron extraction, which is correlated with the regulated energy level alignment and contact quality of E-SnO2/active layer. As a result, considerable power conversion efficiencies (PCEs) of 10.30%, 13.93% and 15.38% for PTB7-Th/PC71BM, PM7/ITC6-4F and PM6/Y6 based OSCs have been realized with E-SnO2 as ETL, respectively. Compared with ZnO based devices, the E-SnO2 based OSCs exhibit an improved light aging stability, which can retain 94.3% of their initial PCE of 15.38% after 100 h light aging for E-SnO2/PM6/Y6 based OSCs. This work demonstrates that the enormous potential of E-SnO2 to serve as ETL for high-efficiency and stable OSCs.