SnO_2–Carbon Nanotubes Hybrid Electron Transport Layer for Efficient and Hysteresis-Free Planar Perovskite Solar Cells

摘要

Tin oxide (SnO_2) has recently received increasing attention as an electrontransport layer (ETL) in planar perovskite solar cells (PSCs) and is considered apossible alternative to titanium oxide (TiO_2). However, planar devices based onpure solution-processed SnO_2 ETL still have hysteresis, which greatly limits theapplication of SnO_2 in high-efficiency solar cells. Herein, to address this issue, ahybrid ETL of SnO_2 and carbon nanotubes (CNTs) is fabricated by a simplethermal decomposing of a mixed solution of SnCl4·5H2O and pretreated CNTs(termed SnO_2–CNT). The addition of CNTs can significantly improve the conductivityof SnO_2 films and reduce the trap-state density of SnO_2 films, whichbenefit carrier transfer from the perovskite layer to the cathode. As a result, a highefficiency of 20.33% is achieved in the hysteresis-free PSCs based on SnO_2–CNTETL, which shows 13.58% enhancement compared with the conventional device(power conversion efficiency ¼ 17.90%).