Manipulating the morphology of CdS/Sb2S3 heterojunction using a Mg-doped tin oxide buffer layer for highly efficient solar cells

Antimony sulfide (Sb2S3) is an appealing semiconductor as light absorber for solar cells due to its high absorption coefficient, appropriate band gap (similar to 1.7 eV) and abundance of constituent elements. However, power conversion efficiency (PCE) of Sb2S3-based solar cells still lags much behind the theoretically predicted due to the imperfect energy level alignment at the charge transporting layer/Sb2S3 interfaces and hence severe charge recombination. Herein, we insert a high-temperature sintered magnesium (Mg)-doped tin oxide (SnO2) layer between cadmium sulfide (CdS) and fluorine doped tin oxide to form a cascaded energy level alignment and thus mitigate interfacial charge recombination. Simultaneously, the inserted Mg-doped SnO2 buffer layer facilitates the growth of the neibouring CdS film with orientation followed by Sb2S3 film with larger grains and fewer pinholes. Consequently, the resultant Sb2S3 solar cells with Mg-doped SnO2 deliver a champion PCE of 6.31%, 22.8% higher than those without a buffer layer. Our work demonstrates that deliberate absorber growth as well as efficient hole blocking upon an appropriate buffer layer is viable in obtaining solution-processed Sb2S3 solar cells with high performance. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

The study inserts a high-temperature sintered Mg-doped SnO2 layer between CdS and fluorine-doped tin oxide to form cascaded energy level alignment, mitigate interfacial charge recombination, and facilitate growth of neighboring films, resulting in a champion PCE of 6.31% for Sb2S3 solar cells.