Low-Temperature and Solution-Processed Amorphous WOx as Electron-Selective Layer for Perovskite Solar Cells

The electron-selective layer (ESL) is an indispensable component of perovskite solar cells (PSCs) and is responsible for the collection of photogenerated electrons Preparing ESL at a low temperature is significant for future fabrication of flexible PSCs. In this work, solution-processed amorphous WOx thin film was prepared facilely at low temperature and used as ESL hi PSCs. Results indicated that a large quantity of nanocaves were observed in the WOx thin film. In comparison with the conventional TiO2 ESL, the WO, ESL exhibited comparable light transmittance but higher electrical conductivity. Compared with the TiO2-based PSCs, PSCs that use WOx ESL exhibited comparable photoelectric conversion efficiency, larger short-circuit current density, but lower open circuit voltage. Electrochemical characterization indicated that the unsatisfied open circuit voltage and fill factor were caused by the hiherent charge recombination. This study demonstrated that this material is an excellent candidate for ESL.