Antimony Doping of CsBi₃I₁₀ for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

Abstract

The CsBi3I10 (CBI) semiconductor as a light absorber emerges as a promising alternative to lead-based perovskites owing to its low toxicity, good stability, and satisfying physical properties. However, CBI exhibits an uncontrollable crystallization process, poor film morphology, high defect density, and short carrier lifetime, which lead to inferior optoelectronic properties, limiting its practical application in solar cell devices. Here, the Sb doping strategy is successfully developed for CBI films by a one-step antisolvent-free fabrication method. It is found that Sb incorporation in binary CsBi3–x Sb x I10 can modulate the crystallization kinetics and optimize the film quality. As a result, polycrystalline films with high density and few pinholes are obtained to enable the enhancement of light absorbance, reduction of defects, suppression of nonradiative recombination, and increase of surface hydrophobicity. The solar cells based on the CsBi2.7Sb0.3I10 film show a remarkably improved power conversion efficiency of 0.82% compared to that of pristine CBI (0.22%), which is among the highest reported efficiencies for CBI-based thin-film solar cells. Moreover, unencapsulated devices based on Sb-doped CBI exhibit outstanding environmental stability and moisture tolerance. This work not only offers insights into understanding the binary Bi-based materials but also provides a new way to fabricate efficient and stable Bi-based solar cells.

Improved Stability of CsBi3I10 Based Pb‐Free Perovskite Solar Cells

“…We have compared our findings with recent literature in Table 1. The obtained results showed that our findings are comparable with previous reports [33–45] …”

“…The lowest PL intensity was observed for FTO/TiO 2 /CsBi 3 I 10 /GO+spiro‐OMeTAD (Figure S3). The lowest intensity suggested the better charge‐extraction and transfer in FTO/TiO 2 /CsBi 3 I 10 /GO+spiro‐OMeTAD compare to the FTO/CsBi 3 I 10 and FTO/TiO 2 /CsBi 3 I 10 [44] …”

“…The lowest intensity suggested the better charge-extraction and transfer in FTO/TiO 2 /CsBi 3 I 10 /GO + spiro-OMeTAD compare to the FTO/ CsBi 3 I 10 and FTO/TiO 2 /CsBi 3 I 10 . [44] Previously, various Pb-free perovskite or perovskite-like materials were reported for the fabrication of PSCs. [28][29][30][31][32][33][34][35][36] We have compared our findings with recent literature in Table 1.…”

“…The obtained results showed that our findings are comparable with previous reports. [33][34][35][36][37][38][39][40][41][42][43][44][45]…”

Cold- and hot-casting to regulate the morphology and charge carrier dynamics of CsBi3I10 towards efficient and stable thin-film solar cells

“…Bismuth (Bi)-based perovskite analogue CsBi 3 I 10 (CBI) exhibits a small bandgap (1.77 eV), high visible light absorption, and excellent humidity tolerance as well as low toxicity, making it become one of the most promising candidates for Pb-free perovskite solar cells. 6,7 Some early attempts such as solvent engineering, 8 additive strategies, 9 element doping 10 and charge transport layer optimization 11,12 have been adopted to further explore and improve the photoelectric properties of CsBi 3 I 10 film solar cells. However, CsBi 3 I 10 is still not dazzling due to its lower PCEs compared to other bismuth-based materials such as Cs 2 AgBiBr 6 , 13,14 Cs 3 Bi 2 I 9 4,15 and AgBiS 2 .…”