Efficient band alignment for ZnxCd1−xSe QD-sensitized TiO2 solar cells

Abstract

Zn_xCd_1−xSe QDs sensitized TiO₂ photoelectrodes on FTO substrates have been prepared using an ion-exchange route. The lattice parameters and band gaps of such Zn_xCd_1−xSe QDs were found to have linear and quadratic relationships with the Zn content (x). These TiO₂/Zn_xCd_1−xSe films were further assembled to solar cells and demonstrated to be promising photoelectrodes for solar cells. In the fabricated QDs sensitized solar cells, QDs with the composition of x = 0.6 produced the highest photocurrent and photoconversion efficiency. It demonstrates that the effective band alignment of the QDs is favorable to enhance the photovoltaic performance for solar cells, by producing an efficient electron–hole separation following a band alignment.