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

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, Cs 2 SnI 6 ), 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 Cs 2 SnI 6 perovskite was done by mixing Cs 2 CO 3 in HI and SnI 4 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 Cs 2 SnI 6 was done by UV-Vis spectroscopy and XRD measurement. In the present experiment, the addition of the Cs 2 SnI 6 layer was performed by spin coating the Cs 2 SnI 6 solution onto the TiO 2 mesoporous layer. The photovoltaic performance of the fabricated DSSC shows a significant enhancement in the short circuit photocurrent density ( J sc ) and conversion efficiency, that is, from 15.04 mA/cm 2 to 16.33 mA/cm 2 from 5.7% to 6.75% due to the incorporation of spin-coated 5 mM Cs 2 SnI 6 in comparison to the reference cell without Cs 2 SnI 6 .