Charge generation and transfer performance enhancement of size-balanced CuInS_2 quantum dots sensitized solar cells

摘要

The optical absorption and charge dynamics of different sized CuInS_2 quantum dots have been investigated. Exact sizes from 2.5 to 4.1 nm of CuInS_2 quantum dots are prepared and further deposited on the TiO_2 films. The optical absorption property of CuInS_2 quantum dots sensitized photo-electrodes are analyzed by UV-Vis spectra, which provides electron generation property of the photo-electrodes. And the electron-hole separation property of the photo-electrodes is characterized by photoluminescence spectra with different size of quantum dots. The electrochemical impedance spectra and time-resolved photoluminescence decay are employed to measure the charge dynamics, which indicates that better electron transfer property can be obtained by the small size of quantum dots. With the balance of charge generation and charge transfer performance, 3.6 nm sized CuInS_2 QDs sensitized photo-electrodes achieves excellent photovoltaic performance.