P-DSSCs with BiOCl and BiOBr semiconductor and polybromide electrolyte

Abstract

BiOCl and BiOBr nanodiscs (100–150 nm in diameter, 15–25 nm in thickness) are prepared via water-based nucleation and purified by a phase-transfer reaction, including oleylamine-induced transfer of the as-prepared nanodiscs from the polar water phase to the non-polar toluene phase. The oleylamine-capping is then removed by hydrazine treatment, and the BiOCl/BiOBr nanodiscs are redispersed in 2-propanol. The as-prepared nanodiscs are finally deposited as a porous, p-type semiconductor layer to obtain dye-sensitized solar cells (DSSCs). Herein, coumarin 343 is applied as sensitizer together with BiOCl as p-type semiconductor and a KI–I2 electrolyte. In addition, eosin Y is applied as sensitizer together with BiOBr as p-type semiconductor and a [C4MPyr]2[Br20] polybromide electrolyte (C4MPyr: N-butyl-N-methylpyrrolidinium). Such polybromide electrolyte is firstly applied in a DSSC and allows for a higher redox potential. Both here established p-DSSCs show the characteristic features and function of a solar cell (BiOCl/coumarin 343/KI–I2: Voc = 120 mV, Jsc = 57 μA cm−2, FF = 40.6%, η = 0.003; BiOBr/eosin Y/[C4MPyr]2[Br20]: Voc = 78 mV, Jsc = 3.1 μA cm−2, FF = 28.6%, η = 0.0005) as a result of this conceptual study.