Effect of annealing temperature and time on the photovoltaic performance of nasbs2 semiconductor-sensitized solar cells prepared by silar method

Abstract

In the search for promising solar absorber materials, ternary metal chalcogenides, such as sodium antimony sulfide (NaSbS2), are considered to be good candidates because of their advantages, such as easy fabrication and tunability of the bandgap. The investigation of the effect of annealing temperature and time as a post-treatment after SILAR was conducted on NaSbS2-semiconductor-sensitized solar cells. The solar cells were prepared by assembling two main components, namely photoanode (TiO2 as a wide gap semiconductor, NaSbS2 semiconductor as a sensitizer, and FTO-glass as a substrate) and counter electrode (Pt). The electrolyte used in this study was polysulfide electrolyte. The results showed that from three variations of annealing temperature (350ºC, 375ºC, and 400ºC), the temperature of 350ºC gave the highest crystallinity (83.50%) and the smallest crystal size (15.26±3.05), and from three variations of annealing time (40 minutes, 50 minutes, and 60 minutes), the time of 60 minutes yielded the highest crystallinity (83.50%) and the smallest crystal size (15.26±3.05); the crystal size mentioned in this research was proved to be the same as particle size based on the TEM picture analysis. Based on these results, the best photovoltaic performance was gained from the NaSbS2 semiconductor-sensitized solar cells prepared by annealing at 350ºC for 60 minutes with the power conversion efficiency (PCE) of 2.04%. The enhancement of PCE comes from the production of electron-hole pairs, the reduced recombination rate of the cells, and the quantum effects exhibited from a more regular crystal and a smaller crystal size.