Abstract
The two-step deposition method effectively mitigates the efficiency decline observed in tin-based perovskite solar cells (TPVSCs) with increasing cell area, stemming from film in-homogeneity. However, the high solubility of SnI2 in the conventionally used solvent isopropyl alcohol, coupled with the absence of effective modulation of reaction-diffusion process, results in inadequate film coverage and conversion. In this study, we introduce formic acid as the second-step solvent and introduce dithiothreitol (DTT) to regulate reaction-diffusion/crystallization kinetics meticulously. Moreover, this research underscores a fundamental principle that the suitable binding energy ranging from -1.38 to -10.10 kcal mol-1 between ligands and Sn2+ significantly enhances the effectiveness of two-step crystallization control. Notably, a uniform perovskite film is achieved on large-scale substrate, and TPVSCs processed with DTT exhibit the highest efficiencies of 12.68 % for 0.04 cm2 device and 11.30 % for 1 cm2 device among tin-based perovskite devices in two-step sequential deposition method, even in the absence of dimethyl sulfoxide. This study lays the groundwork for the potential scale-up development of lead-free perovskite solar cells.
Published Version
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