Study Of The CdSeTe Ternary Alloy Quantum Dots Sensitized Solar Cells Modified By POSS

As the third generation of new solar cell,quantum dots sensitized solar cells(QDSSCs)have the advantages of high theoretical photoelectric conversion efficiency,low manufacturing cost and simple preparation technology.However,the current photoelectric efficiency of QDSSCs is far lower than the theoretical efficiency.Therefore,it's always be the focus of current research that how to improve photoelecrtic efficiency of QDSSCs.In this paper,CdSeTe quantum dots(QDs)with absorption range reaching 750 nm were obtained by optimizing the preparation process.The surface of CdSeTe QDs were modified by Octa-aminoproply polyhedral oligomeric silsesquioxane(OA-POSS).On this basis,QDs were adsorbed on Ti O₂films to prepare photoanode,then assembled into QDSSCs.The influences of the modification of OA-POSS on the photoelectric performance of CdSeTe QDs and QDSSCs were studied.Finally,the preparation processes of QDSSCs were optimized to improve the photoelectric performance.The research contents are as follows:(1)CdSeTe ternary alloy QDs were synthesized by aqueous phase method.The effects of preparation technology on the optical properties of QDs were studied.The results showed that the absorption edge of CdSeTe QDs can reach 750 nm when heating time was 4 h,condensation reflux temperature was 100?,N-acetyl-L-cysteine:Cd=1.2,Cd:(Se+Te)=5,Se:Te=7:3,and p H=11.The time stability and light stability tests showed that the prepared CdSeTe QDs had good stability.(2)OA-POSS were introduced to modify the surface of CdSeTe QDs.The QDs were characterized by thermogravimetric curves,XRD,TEM and EDS.The photovoltaic performance of QDSSCs were tested by using QDs as photosensitizer.The preliminary test of photovoltaic performance showed that the photocurrent density of QDSSCs was increased from 2.29 m A/cm²to 3.40 m A/cm²,and the efficiency of QDSSCs was increased from 0.53%to 0.81%,with an increase of 52.8%after modification.Through process optimization,J-V test of QDSSCs showed that the cell efficiency could be improved from 1.69%to 2.59%,with an increase of52.8%after OA-POSS modification,which provided a simple and effective method to improve the photoelectric performance of QDSSCs.(3)Performance optimization of QDSSCs:the influence of electrolyte composition on the photoelectric performance of QDSSCs was studied.The results showed that the concentrations of Na₂S·9H₂O,S and KCl were 1 mol/L,1 mol/L and0.1 mol/L,respectively,and the volume ratio of water to methanol in the solvent was6 to 4,the efficiency was the highest(1.11%).The effect of Ti Cl₄on the photoelectric properties of QDSSCs was studied.It was found that when the surface modification time of Ti Cl₄was 90 minutes,the photoelectric properties of QDSSCs was the best,and the cell efficiency could reach 1.61%.The surface of QDs/Ti O₂was passivated by successive ionic layer adsorption and reaction.The effects of ZnSe/ZnS and CdS/ZnS on the photoelectric properties of QDSSCs were studied respectively.The results showed that CdS can reduce the lattice distortion between QDs and ZnS layer more effectively.The influence of layer thickness on the photoelectric properties of QDSSCs was studied,which found that the best successive ionic layer adsorption and reaction cycle times for the preparation of ZnS and CdS were 4 and 2,respectively.