| Solar cells have been widespread concern by the researchers because solar cells as a photovoltaic conversion device have achieved the effective use of solar energy.Quantum dot sensitized solar cells(QDSCs)have become the most promising photovoltaic devices in the field of solar cells because of their accessible electrode materials,low cost,simple preparation process and high photovoltaic efficiency.In recent years,QDSCs photovoltaic efficiency have been improved,but how to ensure its high photovoltaic performance and good stability simultaneously are the key of ultimately realizing QDSCs’ commercial development.In this paper,a series of benzimidazolium organic ion conductors were used as the solid-state electrolytes of QDSCs,which were aimed at limiting the decay of the photovoltaic performance caused by the volatile and leakage of liquid electrolyte.The research work of this paper is divided into two parts:In the first part,three different anions of benzimidazolium organic ion conductors[DHexBIm]X](X=Br,BF4,SCN)were designed and synthesized,and then other additives were added into these conductors to prepare solid-state electrolytes.These solid-state electrolytes were used in QDSCs and the photovoltaic performance of QDSCs were tested subsequently.Meanwhile,the stability of the optimal cell performance was compared with liquid QDSCs.The structures of the conductors were characterized by 1H NMR,13C NMR,MS and IR.The electrochemical performance of the cells were investigated by J-V,EIS,CV,Tafel and IPCE.The performance of the conductors were investigated by XRD,thermal analysis,SEM and conductivity measurement.Experiment results showed that:[DHexBIm][X](X=Br,BF4,SCN)conductors within the measurement temperature range of solar cells all have good thermal stability,crystallinity and high conductivities.As solid-state electrolytes used in QDSCs,they all have obtained better photovoltaic performance compared to other solid-state electrolytes.Particularly,[DHexBIm][SCN]conductor displayed a useful solid-solid phase transition at 50 ℃ and a high conductivity.QDSCs based on[DHexBIm][SCN]acquired a short-current density(Jsc)of 12.58 mA/cm2,an open-circuit voltage(Voc)of 0.60 V,a fill factor(FF)of 56.44%,and a power conversion efficiency(PCE)of 4.26%under standard light intensity(AM 1.5G,100 mW/cm2),and the cell maintained good stability over 504 h.The good ionic conductivity and the low value of RCE caused the Jsc of 12.58 mA/cm2.Meanwhile,the Rs played a major role in the enhancement of FF,which made more contribution to the photovoltaic efficiency of[DHexBIm][SCN]-based cell.This research throws a new light on the development of the solid-state electrolyte materials in QDSCs and possed some useful value.In the second part,I have developed a series of different size and structure of benzimidazolium dication conductors C5EtBIm2,C6EtBIm2 and C6PrBIm2.Then,the structure and performance of the materials were characterized by 1H NMR,13C NMR,MS,IR,XRD,thermal analysis and SEM.The results showed that I have achieved the target products by synthesis and they all have good thermal stability and crystallinity.The solid-state electrolytes were prepared by using the dication conductors as solid-state matrix with other additives added simultaneously.By testing their conductivities,These electrolytes were applied to QDSCs with cell performance testing by J-V,EIS,OCVD and IPCE.The research results showed that QDSCs based on dication conductors have better photovoltaic performance compared with other solid QDSCs.Specially,the QDSCs based on C5EtBIm2 was reached a short-current density of 13.12 mA/cm2 and a power conversion efficiency of 4.11%under(AM 1.5G,100 mW/cm2)solar irradiation.The solid QDSCs still maintained the initial efficiency of 74.45%within 168 h,with good stability.This research throws a new light on the development of the high performance and good stablity solid-state electrolyte materials in QDSCs and possed some useful value. |
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