Preparation And Photovoltaic Performance Of ZnO Based Quantum Dot Sensitized Solar Cells

Quantum dots sensitized Solar cell?QDSSCs?is paid continuous attention by the vast researchers due to its many many merits,such as simple preparation,quantum confinment effect,multi-exciton effect.However,Currently,the highest efficiency of QDSSCs is further less than its theoretical conversion efficiency,thus there are tremendous development potential to improve the photovoltaic performances of QDSSCs.In accordance with the above key scientific issues,the ZnO semiconductor was used as photoanode film and the preparation parameters of CdS/CdSe co-sensitived quantum dots solar cells were studied in this paper.XRD,SEM,UV,XPS and EDS were used to characterize ZnO photoanode and Cu2S counter electrode.The I-V curves of the QDSSCs under different experimental conditions were also tested.The main concludes were as followings:?1?The influence of three kinds of ZnO photoanode films with different morphologies on the performance of CdS/CdSe QDSSCs were studied.The more smooth,bigger specific surface area and more porosity of the morphology of ZnO photoanode film,the better photovoltaic performance of the device will achieve accordingly.The performances of photoanode film with ZnO nanobelts are better than ZnO nanosheets,but lower than ZnO microspheres.?2?The influence of sythesis parameters of CdS and CdSe qunatum dots on the performance of the devices fabricated with Pt counter electrode were studied.When the precursor solution concentration of CdS was 0.1 M,deposition five times,the device of CdS QDSSCs achieved the best efficience of 0.21%.While the deposition time of CdSe was 3 h,the Voc,Jsc,FF and PCE of the CdS/CdSe QDSSCs were 0.37 V,9.98 mA/cm²,0.26 and 0.96%,respectively.?3?The influence of Cu₂S counter electrode on the performance of QDSSCs under different prepapation conditions were studied.The mechanical performance of Cu₂S counter electrode would be not stable if it was treated more than 60min in strong hydrochloric acid at 80?.Briefly,the surface of Cu₂S counter electrode were prone to falling off under the action of electrolyte,which may"pollute"the photoanode film and turn them black.Here,we speculated that the tiny black objects were the compounds of copper sulfur,namely Cu_2-xS.When the brass foils were treated by strong hydrochloric acid for 30 min,Cu₂S counter electrode has the best electrical catalytic performance.Meanwhile,the photoelectric conversion efficience of QDSSCs without the passivation layer was 1.94%.the Voc,Jsc and FF of CdS/CdSe QDSSCs were 0.49 V,11.06 mA/cm² and 0.36,respectively.In addition,It can obviously improve the photovoltaic performance of solar cells through introduction of ZnS and ZnSe passivation layer.The efficiency of QDSSCs with double passivation layers of ZnS and ZnSe was 4.60%.the Voc,Jsc,FF of CdS/CdSe QDSSCs were 0.54 V,17.10 mA/cm² and 0.50,respectively.