CdSe quantum dot-sensitized solar cell: Effect of size and attach mode of quantum dot

Different size of colloidal CdSe quantum dot (QD) was synthesized through a simple solvothermal route and their structural, morphological and optical properties were characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), UV-visible absorption spectroscopy and fluorescence spectrometer. XRD and TEM measurement confirmed the formation of CdSe QDs. The red shift of absorption and fluorescence peaks indicated that the size of CdSe QDs increased with prolonging reaction time. The size of QDs varied from 2.2 nm to 3.4 nm by varying reaction time from 1 h to 7 h. The absorption spectra of CdSe/TiO2 electrodes proved that the loading of CdSe QDs on TiO2 can be greatly improved by MPA pretreatment. The effect of size of CdSe QDs on the performance of CdSe QDs sensitized solar cells was investigated. Due to the change of absorption range in the visible region and the conduction band shift for different size of CdSe, the photo-electric power conversion efficiency first increased and then decreased with increasing size of CdSe. The devices fabricated with 3.1 nm diameter CdSe nanoparticles exhibited the highest conversion efficiency of 0.70% under AM 1.5 G irradiation (100 mW cm(-2)).