Dip‐Coated SnO2 Electron Transport Layer for Efficient and Stable PbS Quantum Dot Photovoltaics

Abstract

Advance in wide‐bandgap‐oxide electron transport layers (WBO‐ETLs) is essential for the development of high‐efficiency and stable solution‐processed quantum dot photovoltaics (PVs). Herein, a novel dip‐coated SnO2 ETL to fabricate PbS colloidal quantum dot solar cells (CQDSCs) is employed, replacing the benchmarked ZnO sol–gel ETL, in pursuit of both high efficiency and high operational stability. Taking advantage of the high light‐transmittance and desired electrical characteristics of the dip‐coated SnO2 ETL, the CQDSC with a structure of fluorine‐doped tin oxide (FTO)/SnO2/I‐capped PbS CQDs/EDT‐capped PbS/Au (EDT: 1,2‐ethanedithiol), exhibits a champion power conversion efficiency (PCE) of 10.70%, higher than the 9.52% of the ZnO‐based control device. Particularly, the unencapsulated SnO2‐based CQDSC demonstrated a remarkably improved operational stability in comparison to the ZnO‐based device, maintaining 93.4% of the initial efficiency after a 200 h light‐soaking at the maximum power point tracking under AM 1.5G irradiation, which is attributed to the robust SnO2/PbS CQD heterojunction under operational conditions. The improved efficiency and operational stability suggest the superiority of the dip‐coated SnO2 ETL to its ZnO counterpart, paving a way for the development of high‐efficiency and high‐stability CQDSCs via WBO‐ETL engineering.