Synthesis And Adsorption CIS Quantum Dots Sensitizer And Perparation Solar Cells

Quantum dot sensitized solar cells?QDSCs?have become the development direction of the next generation solar cells because of their unique photoelectric characteristics,such as good light,heat and humidity stability,wide absorption range,high absorption coefficient and the possibility of generating multiple excitons.At present,QDs sensitizer are mainly composed of a group II-VI,III-V,IV-VI,I-III-VI semiconductor compound.CuInS₂ quantum dots in I-III-VI group elements are a direct band gap semiconductor compound with high absorption coefficient,low toxicity and optimal band gap energy?1.5 eV?which is considered as an ideal optical absorption material to replace II-VI group quantum dots.CuInS₂?CIS?and Zn-CuInS2?Z-CIS?quantum dots were synthesized by thermal injection method,and then high performance CIS and Z-CIS QDs were used as sensitizers for quantum dot sensitized solar cells,which could lay a foundation for their future applications in the field of solar cells.This paper mainly research topics include:?1?CIS QDs is synthesized with four different source precursor solution.Four different source precursor solution:sulfur powder was dissolved in oleylamine?OAm?,1-octadecene?ODE?,diphenyl phosphine?DPP?,and N,N'-Diphenylthiourea?N,N'-DP?was dissolved in diphenyl ether,respectively.Metal precursor solution copper iodide?CuI?and indium acetate?In?OAc?₃?were dissolved in a mixed solution containing OAm and ODE in a flask and the resulting mixture was heated to180°C.The results show that CuInS2 quantum dots?CIS QDs?synthesized by ODE-S as sulfur precursor solution have better crystallinity structure and longer the photon-generated carrier life.?2?At the same time,sulfur powder is more soluble in oleylamine during the preparation process,and the required dissolution temperature is lower and better dissolved.Therefore,CIS QDs synthesized with OAm-S has enormous amount of research effort.We adopted a series of heating strategies to hot-injection the sulfur source precursor solution at 120,150,180,210,and 240°C.It is found that the TEM shows the quantum dot size becomes larger as the temperature increases.In order to deposition the QDs on the TiO₂ substrate,we choose the ligand exchange method to convert the OAm-capped oil-phase quantum dots into MPA-capped water-phase quantum dots,and FT-IR and XPS spectrum shows that the oil-to-water strategy is successful.?3?In order to increase the loading of the QDs aqueous phase on the TiO₂substrate,adjust the pH of the QDs aqueous solution,solution concentration of QDs and the deposition time.UV and IV results show that the maximum loading amount on the TiO₂ substrate when the concentration of the solution is 0.2 M and the deposition time is 3 hours.The wide-band gap material ZnS is used to wrap the photoanode to prevent the direct contact between the photoanode and electrolyte,which is an effective method to reduce the electron recombination loss at the photoanode/electrolyte interface.IV test results show that the open-circuit voltage and short-circuit current density are significantly increased,which further proves the reduction of interface recombination.Choosing different copper-indium ratios can reduce the defect density of quantum dots and improve the efficiency of batteries.Different copper-indium ratios can be selected.Increasing the content of indium decreases the density of defect states on the surface of quantum dots and the bandgap of CIS quantum dots.At the same time,it is found that the synthesized Z-CIS alloy structure has fewer defects,which can effectively reduce the charge recombination probability and ultimately improve the photoelectric conversion efficiency of the battery.