Effect of Lead-Free Perovskite Cs<sub>2</sub>SnI<sub>6</sub> Addition in the Structure of Dye-Sensitized Solar Cell

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Over the past few years, metal halide perovskites have been considered as a promising material for application in photovoltaic devices because of its unique optical and electrical properties. In particular, Sn-based perovskites have been being considered to replace Pb-based perovskite because of the Pb toxicity that will raise serious concerns on the environmental issue. In this report, we present our attempt to synthesize the Sn-based perovskite (namely, Cs2SnI6), which is air and thermal stable, and use it as an electron transport layer in dye-sensitized solar cells (DSSC) for improving its power conversion efficiency. The synthesize of Cs2SnI6 perovskite was done by mixing Cs2CO3 in HI and SnI4 in ethanol to form a precipitate at room temperature. The purification process was an important part to collect effectively the synthesis product. The fabrication of DSSC was done by a standard process based on the screen printing and spin-coating techniques, while the characterization of Cs2SnI6 was done by UV-Vis spectroscopy and XRD measurement. In the present experiment, the addition of the Cs2SnI6 layer was performed by spin coating the Cs2SnI6 solution onto the TiO2 mesoporous layer. The photovoltaic performance of the fabricated DSSC shows a significant enhancement in the short circuit photocurrent density (Jsc) and conversion efficiency, that is, from 15.04 mA/cm2 to 16.33 mA/cm2 from 5.7% to 6.75% due to the incorporation of spin-coated 5 mM Cs2SnI6 in comparison to the reference cell without Cs2SnI6.