A bithiophene-cored interfacial passivating layer for Sb2S3 solar cells with 7.1% efficiency

Sb2S3 , which is an excellent performance of the third generation of solar cells with superior photovoltaic properties, high stability and environmental friendliness. However, because of the low formation energies of the cation-replaced-anion antisites and anion vacancies, the presence of these trap states result in increased unpaired Sb atoms, which could serve as charge recombination centers on the surface and grain boundaries. Here, we introduce a bithiophene-cored compound (BTR-TPA, 4,4'-([2,2 '-bithiophene]-5,5 '-diyl)bis(N,N-bis(4-methox-yphenyl)aniline)) as an interlayer between the Sb2S3 and hole transport layers to passivate the trap states. Suitable energy levels, inhibited antimony oxide impurity phase, low trap states together with remarkable photoelectric properties are obtained via introducing such an interface layer. As a result, the optimal power conversion efficiency (PCE) of Sb2S3 solar cells is raised from 6.25% (control device) to 7.12%. This research demonstrates that interface passivation is an effective means of enhancing the PCE of Sb2S3 solar cells.