Green Synthesis of CdS/CISe Core-Shell Structured Quantum Dots and Their Photovoltaic Applications

Quantum dots (QDs) of I-III-VI2 ternary compounds, such as CuInSe2 (CISe) and CuInS2 (CIS), have broad application prospects as light-absorbing layers in solar cells due to their excellent photoelectric properties. Nevertheless, the presence of large numbers of surface defects in quantum dots will affect their performance. In this study, inverted type-I CdS/CISe core-shell QDs are successfully synthesized through thermal injection method in triethylene glycol, which is green and safe. By changing the molar ratios of CdS and CISe QDs, the components and optical properties of core-shell QDs are intensively studied by using different characterization methods (XRD, TEM, EDS, UV-vis, Raman, and fluorescence spectrum). The solar cells with the structure of FTO/TiO2/CdS/CdS/CISe/Mo are assembled, where the CdS/CISe core-shell QDs are used as absorption layers. The prepared devices exhibit an efficiency of 1.01% under an AM 1.5 G spectrum with a light intensity of 100 mW cm-2. Inverted type-I CdS/CISe core-shell quantum dots are synthesized through the thermal injection method in a green system. The CdS/CISe quantum dots exhibit quantum effects associated with the CISe shell layer. Schottky solar cells packaged with CdS/CISe core-shell quantum dots show better performance, with Jsc, FF, and PCE increased to 0.56 mA cm-2, 0.44, and 1.01% respectively.image