Interface Structure Of Quantum Dot-sensitized Nanocrystalline Thin Film Electrodes And Performance Of Solar Cells

The use of nanometer sized semiconductor as the photosensitizer to construct quantum dot sensitized solar cell(QDSSC)is a new type solar cell that have been attracted much attentions in recent years,whereas the enhancement of its performance of QDSSC is currently the main topic.In this synthesis,the interface structure of CdSe quantum dot sensitized Ti02 film was controlled by producing the CuxS hole transport layer and surface passivation,and their effects on the performance of the resulted QDSSC have been studied.The main works are as follows:1.CdSe quantum dots were synthesized and tethered on Ti02 surface to form CdSe quantum dot sensitized Ti02 film electrode.After surface treatment with the successive ionic layer adsorption and reaction(SILAR),Cu2+ion exchange were performed to form CuxS hole transport layer.The structure and optical properties of the film were further characterized by SEM、UV-vis、PL measurements.2.The CdSe quantum dot sensitized Ti02 electrodes were assembled to QDSSCs,and their solar to electricity and the kinetics of the potogenerated charge carriers were studied by measuring the J-V,IPCE as well as EIS,IMVSand IMPS.Results show that,due to the formation of CuxS hole transport layer through Cu2+ ion exchange,the hole transfer is increased and charge recombination is reduced,resuting in a large enhancement of PCE of the cell.The PCE of the QDSSC increased from 5.63%for the cell before Cu2+ion exchange to 6.92%after Cu2+ion exchange,showing an 23%increasement.3.Surface passivation were performed on TiO2/CdSe photoanode,and its effect on the cell efficiency of CdSe QDSSC were studied.Photovoltaic measurements show that,the cell efficiency with ZnS passivation is better than the cell with ZnSe passivation,and the ZnS,ZnSe double passivation is more favorable than either ZnS or ZnSe passivation for enhancing the cell efficiency of the QDSSC.The best cell efficiency of 6.83%was achieved with ZnS/ZnSe passivation,showing an17%increment as compared to ZnS passivation.EIS,IPCE,IMVSand IMPS measurements indicate that,the interface and energy band can simultaneously be optimized through the double passivation,which lead to the increase of hole transfer rate and the decrease of charge recombination.And consequently enhanced the solar energy conversion efficiency of the QDSSC.