Improving the Photocurrent in Quantum-Dot-Sensitized Solar Cells by Employing Alloy PbxCd1−xS Quantum Dots as Photosensitizers

Ternary alloy PbxCd1-xS quantum dots (QDs) were explored as photosensitizers for quantum-dot-sensitized solar cells (QDSCs). Alloy PbxCd1-xS QDs (Pb0.54Cd0.46S, Pb0.31Cd0.69S, and Pb0.24Cd0.76S) were found to substantially improve the photocurrent of the solar cells compared to the single CdS or PbS QDs. Moreover, it was found that the photocurrent increases and the photovoltage decreases when the ratio of Pb in PbxCd1-xS is increased. Without surface protecting layer deposition, the highest short-circuit current density reaches 20 mA/cm² under simulated AM 1.5 illumination (100 mW/cm²). After an additional CdS coating layer was deposited onto the PbxCd1-xS electrode, the photovoltaic performance further improved, with a photocurrent of 22.6 mA/cm² and an efficiency of 3.2%.