Efficient quantum dot-sensitized solar cell with tunable energy band CdSexS(1−x)quantum dots

Abstract

Tunable energy band CdSe_xS_(1−x) quantum dots (QD) are developed for QD-sensitized solar cells(QDSSCs) by the successive ionic layer adsorption and reaction (SILAR) technique. The results indicated that the energy band and the light absorption of CdSe_xS_(1−x) QDs could be controlled by the ratio of the sulphur (S) and the selenium (Se). Compared with the conventional CdS/CdSe system, its absorption spectrum and monochromatic incident photon-to-electron conversion efficiency (IPCE) spectrum show higher light harvest ability and a broader response wavelength region. As a result, a high energy conversion efficiency of 2.27% was obtained with the CdSe_xS_(1−x) QDSSCs under AM 1.5 illumination of 100 mW cm⁻². After being further treated with CdSe QDs, the CdSe_xS_(1−x)/CdSe QDSSC yielded an energy conversion efficiency of 3.17% due to the enhanced absorption and the reduced recombination. It can be expected that tunable energy band QDs controlled by the ratio of atoms can contribute to higher efficiency QDSSCs.