Surface modification on nanoripple-like ZnO nanorod arrays using two-dimensional (2D) Bi2OS2 to fabricate high-performance inverted polymer solar cells

Abstract

In this paper, three-dimensional (3D) nanoripple-like ZnO nanorod arrays (R-ZnO NRAs) are successfully fabricated and modified by two-dimensional (2D) Bi2OS2 material, and inverted polymer solar cells (IPSCs) with R-ZnO modified by Bi2OS2 as electron transmission layer (ETL) are fabricated for the first time. The results show that the surface morphologies of R-ZnO NRAs can be controlled by adjusting the concentration of the modified 2D Bi2OS2 solution. Bi2OS2 modification can not only suppress the surface defects of R-ZnO NRAs, reduce the recombination of photogenerated charges, but also increase crystallinity of the active layer, resulting in effective electron collection. And thus, the performance of IPSCs is obviously improved. The power conversion efficiency (PCE) of PTB7: PCBM based PSCs with R-ZnO NRAs modified by 2% Bi2O2S as ETL is considerably raised to 7.31% from 5.51%. More interestingly, Bi2OS2 modification enhances IPSCs stability to remain 80.9% of their initial PCE after 80 days, yet IPSCs with pristine R-ZnO NRAs remain only 47.4% of their initial PCE. Moreover, this approach can also successfully improve the performance of another IPSC composed of PBDB-T: ITIC blends. The PCE of the device based on 2% Bi2OS2-modified R-ZnO NRAs is improved to 9.94% from 8.03% of the reference device without Bi2OS2 modification. This work not only provides an effective mean of surface modification of R-ZnO NRAs, but also shows the Bi2OS2 material has potential application in PSCs.