Hybrid interfacial ETL engineering using PCBM-SnS2 for High-Performance p-i-n structured planar perovskite solar cells

Abstract

Fullerene derivatives, such as PCBM i.e. [6,6]-phenyl C61 butyric acid methyl ester, are actively used as electron-transport layers (ETL) in inverted perovskite solar cells (PSC). However, limitations, such as low electron transportation, large electron trap region, poor film formation, and profuse non-radiative recombination, at the perovskite/PCBM interface result in relatively low performance in inverted PSC. Herein, a significant strategy to overcome these challenges was envisaged via using tin disulphide (SnS2) combined with PCBM, forming a uniform mixture of PCBM-SnS2 with high electron transportation and favorable energy levels. In addition, the greater relative permittivity of SnS2 permits shrinkage in critical electron captured radius from 0.62 nm to 0.22 nm, thus reducing leakage current and non-radiative recombination at the perovskite/PCBM-SnS2 interface. The efficiency of PCBM-SnS2 ETL based inverted PSC reached up to approximately 20% having a high 82% fill factor along with improved internal and external quantum efficiencies. The PCBM-SnS2 ETL reduced the charge transportation resistance and increased recombination resistance. The device stability was improved due to increased hydrophobicity and electrical compactness of the PCBM-SnS2. Hence, the synergetic effect of PCBM-SnS2 as an efficient ETL has great potential in improving the performance of planar inverted PSC.