Determination of critical total secondary phase densities in CZTS and investigation of their effects on the perovskite solar cell performance with CZTS as an HTL

Abstract

Inorganic Cu2ZnSnS4 (CZTS) nanoparticles have attracted attention as an HTL in the solution-based perovskite solar cells. CZTS is comprised of non-toxic and abundant elements in nature but the secondary phases formed in CZTS have a detrimental effect on its performance. In quaternary CZTS compounds, secondary phases can affected on the solar cell performance drastically. In this paper, we investigate the effects of Sn-based secondary phases on the main parameters of a CZTS/perovskite/TiO2/FTO solar cell structure. For this purpose, we considered the secondary phases at CZTS bulk and the CZTS interface with the perovskite. We used the experimental data for our numerical methods to study the effect of secondary phases on the performance of the PSC. The obtained data shows that the negative effects of secondary phases that present in the interface are much greater than their effects on a bulk CZTS. It was found that SnS2 and Cu2SnS3 had more negative effects than other secondary phases, and SnS had the least effects on solar cell performance. The results were predict that the optimal thickness of HTL is 200 μm, and if the total defects density at the interface between CZTS and perovskite reaches 1013 or higher, its critical values, in this case, the performance of the perovskite solar cell is severely impaired. The final results provide a good understanding of the performance of secondary phases in HTL, is in good agreement with the results reported with other experimental papers, and indicate the need to remove the secondary phases from the CZTS structure.