| In recent years,new perovskite materials have shown excellent performance in a variety of optoelectronic d evices,and have become one of the research directions that have attracted increasing attention in the field of semiconductors.In the early stage,people focused on the organic-inorganic hybrid perovskite material.However,due to the poor thermal stability and volatilization of its organic parts,this material has long-term stability problems.When the organic cation is replaced by inorganic cesium ion,the perovskite material has higher intrinsic stability,when the perovskite material is close to or less than its exciton Bohr radius,it has a quantum confinement effect.Inorganic perovskite is one of the current research frontiers and hot issues.In this paper,all inorganic perovskite semiconductor(CsPbBr3)quantum dot materials are selected.Based on the experimental phenomenon of the fluorescent life of the quantum dot film that changes with the substrate,the non-radiative energy transfer(NRET)process in the CsPbBr3 quantum dot-Si composite structure was systematically studied,and the NRET process with high quantum yield was obtained through the adjustment of structural parameters.Furthermore,a prototype solar cell device based on the CsPbBr3 quantum dot-Si composite structure is designed and prepared.The NRET process is used to improve the collection efficiency of photogenerated carriers of solar cells,thereby improving the photoelectric conversion efficiency of silicon-based photovoltaic devices.The main work of the paper is as follows:1.We have prepared all inorganic perovskite quantum dots(CsPbX3,X=Cl,Br,I)with high crystallinity,single morphology and narrow size distribution by high temperature heat injection.By changing the ratio of reactants,reaction temperature and time,we have realized the regulation of wavelength range from 400nm to 685nm,and obtained thickness controllable and uniform density CsPbBr3 quantum dot films on quartz and silicon substrates by spin coating method.The fluorescence peak wavelength and half peak width of CsPbBr3 quantum dot films were 515nm and 18nm respectively.The time-resolved fluorescence spectra of CsPbBr3 quantum dot films on different substrates were measured at the same time.The results showed that the fluorescence lifetime on quartz was 25.91ns,while that on silicon was only 4.24ns.It was found that there was a fast state NRET process in the CsPbBr3-Si composite structure.2.Alumina is introduced as the spacer between the CsPbBr3 quantum dots and the silicon substrate.The dependence of carrier fluorescence life on quantum dot size,luminescence wavelength,spacer thickness,substrate refractive index and other structural parameters in CsPbBr3 quantum-Si composite structure are theoretically calculated.The experimental results were in good agreement with theoretical results.The results show that when the distance of the spacer layer is less than or equal to 20 nm,the NRET process is dominant,and when the spacer layer is greater than 20 nm,the radiative emission is dominant.Furthermore,we defined the quantum yield(QY)of the NRET process.When the thickness of the alumina is 0 nm,the QY can reach up to 86.8%.3.The composite structure of CsPbBr3 quantum dots-Si nanowires(CsPbBr3 QDs-Si NWs)was proposed.Through the optimization of structural parameters,the NRET process QY of the composite structure reached up to 82.8%.The prototype solar cell device of Al/Si NWs@Al2O3/CsPbBr3 QDs/Spiro-OMeTAD/Ag schottkey junction was further designed and prepared.The NRET process in the CsPbBr3 QDs-Si NWs composite structure was utilized to effectively reduce the charge loss caused by the defect state capture effect when the carrier passed through the interface and improve the collection efficiency of photogenerated carriers.Compared with the structure without CsPbBr3 quantum dots,the short-circuit current density of solar cells increased from 25.90 mA/cm2 to 30.21 mA/cm2,and the photoelectric conversion efficiency increased from 7.26%to 7.93%. |
PDF Full Text Request