Charge generation performance enhancement by size-dependent Cu2GeSe3 quantum dot-sensitized solar cells

Cu2GeSe3 quantum dot is introduced to instead of non-toxic CuInSe2 as a sensitizer for solar cells, which is employed to enhance the photovoltaic performance. Cu2GeSe3 quantum dots with various sizes are prepared by thermolysis process, which are employed for the fabrication of quantum dot-sensitized solar cells (QDSSC) according to assembly linking process. The optical absorption properties of the Cu2GeSe3 quantum dot-sensitized photo-electrodes have been obviously enhanced by the size optimization of quantum dots, which are better than that of CuInSe2-based photo-electrodes. Due to the balance on the deposition quantity and charge transfer property of the quantum dots, 3.9 nm-sized Cu2GeSe3 QDSSC exhibits the highest current density value and incident photon conversion efficiency response, which result in a higher photovoltaic conversion efficiency than that of CuInSe2 QDSSC. The modulation of Cu2GeSe3 QDs will further improve the performance of photovoltaic devices.