Bi2Ti2O7/PbCdS2/PbS solar cells with NiS@rGO Electrocatalyst: A strategy for enhancing light absorption and polysulfide reduction

Abstract

The pyrochlore structure of bismuth titanate (Bi2Ti2O7) has been used as a photo-anode to fabricate PbCdS2 sensitized solar cells. The ternary PbCdS2 alloy has been coated with the thin Bi2Ti2O7 (BTO) films by optimizing the successive ionic layer adsorption and reaction (SILAR) cycles. The structure and chemical composition have been identified through X-ray diffraction and X-ray photoelectron spectral analysis. The nanorods-like morphology has been observed from the morphological analysis. J-V results demonstrate that the BTO/3PbCdS2 with NiS counter electrode (CE) cell has a better power conversion efficiency (PCE) of 1.03 % with a JSC of 4.56 mA cm−2, VOC of 49 mV, and FF of 0.39, which is superior to other BTO/PbCdS2 combinations and pristine CdS and PbS. Furthermore, the PCE is increased by sandwiching the NiS-rGO CE with the BTO/3PbCdS2/Sn2-/S2- and attaining a maximum JSC of 5.65 mA cm−2, VOC of 539 mV, FF of 0.56, and PCE of 2 %. The obtained FF and are 43 % and 94 % higher than the BTO/3PbCdS2/Sn2-/S2-/NiS cell, respectively. The improvement is owing to increased light absorption, perhaps due to a favorable band position, lower carrier recombination, and the effective polysulfide reduction of NiS-rGO. The results suggest that optimized SILAR cycles are not the only approach to attaining a superior PCE; implanting an effective electrocatalyst is also a viable option.