Magnetron Sputtered SnO2 Constituting Double Electron Transport Layers for Efficient PbS Quantum Dot Solar Cells

Abstract

Herein, for the first time, it is successfully demonstrated that radio frequency (RF) magnetron sputtered SnO2 can be a qualified alternative electron transport layer (ETL) for a high‐efficiency PbS quantum dot (QD) solar cell. The highest performing device using such a SnO2 ETL obtains an efficiency of 8.4%, which is comparable to the sol–gel ZnO‐based one (8.8%). The excellent performance mainly results from the improved current density, which is attributed to the superior properties of the SnO2 ETL, such as high electron mobility and excellent optical transmittance. However, it is also found that the sputtered SnO2‐based devices show smaller voltage and fill factor due to the unsatisfied surface morphology and energy level alignment. By combining a thin (around 10 nm) sol–gel ZnO film on top of a sputtered SnO2 film to form the double ETL, the best efficiency of 10.1% is obtained, which is the highest efficiency using SnO2 ETL in a PbS QD solar cell. The work not only provides a new avenue to improve the efficiency of PbS QD solar cells but also offers the possibility to use an industry compatible sputtering technique for PbS QD solar cells.