Research For Silicon Passivation ZCIS QDs And Cu₂S Nanowire Counter Electrode In QDSCs

From the research of the first generation of Silicon solar cells,solar cells have experienced a lot of improvement projects from generation to generation.Quantum dot-sensitized solar cells(QDSCs)have become one of the most concerned batteries in the third generation solar cells with their good photoelectric properties.Quantum dots(QDs)have excellent optoelectronic properties,such as size-adjustable and high extinction coefficients,and also have proved to be one of the ideal candidates for low-cost and high-performance applications.We can see from the analysis of the research progress in the past twenty years that binary quantum dots have been widely studied such as CdS,CdSe,PbS and PbTe.But heavy metals such as cadmium and lead in quantum dots have serious environmental pollution,so low toxicity ternary quantum dots have been widely developed,like Cu-In-Se and Cu-In-S.The four-element alloying QDs,ith its simple manufacturing steps and high photoelectric conversion efficiency,has entered the researchers' field of view in the past five years,such as Zn-Cu-In-S and Zn-Cu-In-Se.There are also advantages of low toxicity,environmental protection and high efficiency in four-element alloying QDs.The current Zn-Cu-In-S alloys QDSCs have achieved good efficiency which directly leads to the interfacial carriers being trapped and compounded before they are transmitted to the outer circuit.Therefore,in order to solve these current problems,this paper mainly studies the passivation of ZCIS alloying QDs to reduce the surface defect density of QDs,thus improving the photoelectric conversion efficiency(PCE)of the battery.At the same time,the catalytic performance of the counter electrode in the battery is another important factor affecting the efficiency of the battery.The research is as follows:1?ZCIS QDs with alloyed structure was synthesized by thermal injection synthesis method,and ZCIS QDs with silicon passivation was successfully synthesized.QDs ligands were exchanged and loaded onto mesoporous TiO2 films,assembled with Cu2S nanowire counter electrodes and polysulfide electrolyte QDSCs.It was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and electrochemical impedance spectroscopy(EIS).The defect density on the surface of the QDs sensitizer after passivation decreases,increasing the rate of electron injection TiO2 conduction band,and effectively suppressing the charge recombination at the interface of photogenerated carriers and QDs/TiO2/electrolytes.The efficiency of the passivated QDSCs 4.89%increased by 49.5%compared with that of the former QDSCs 3.27%.2?Cu2S nanowire counter electrode was synthesized by a special synthesis method.Cu(OH)2 nanowire array was synthesized on the surface of brass sheet,than Cu(OH)2 was converted into Cu2O by high temperature annealing,finally vulcanized to obtain Cu2S nanowires which was then assembled into QDSCs as the counter electrode to measure the energy conversion efficiency.The SEM?TEM and current-voltage(J-V)curves were characterized.The analysis concluded that the improvement of the PCE may be due to the increased contact area between the Cu2S nanowire counter electrode and the electrolyte,thus increasing the catalytic active sites,the redox rate and short-circuit current density(Jsc).