Exploration Of Novel Photovoltaic Devices Based On Perovskite Quantum Dots-Silicon Based Hybrid Structures

A 11-Inorganic Perovskite（A IP）quantum dots,as a new type of low-dimensional semiconductor material,not only reduce the cost of preparation by eliminating the need for core/shell cladding,but also exhibit excellent optoelectronic properties such as intense light absorption and photoluminescence（PL）,narrow-band emission as well as tunable emission,high quantum yield of luminescence（QY）and more.Furthermore,because of its good stability and low impact on light,heat,water and other environments,it makes all-inorganic perovskite quantum dots have a broad development prospect in the field of photovoltaic devices and become a new research hotspot.In this thesis,C sPbX 3（X=C 1,B r,I）inorganic perovskite quantum dots were used as the research object,based on the observed changes in the luminescence lifetime of quantum dot films on different substrates,and the N onR adiative E nergy T ransfer（N R E T）process in the chalcogenide quantum dot-silicon hybrid structure was systematically investigated.Further,a prototype solar cell device based on C sPbB r3 quantum dot-silicon nanowire hybrid structure is constructed to effectively improve the photogenerated carrier collection efficiency of the silicon-based solar cell using the N R ET process,thereby increasing the power conversion efficiency of the cell.T he research content of this thesis includes:1.All-inorganic chalcogenide quantum dots with tunable components C sPbX3（X=Cl,B r,I）were prepared by high-temperature thermal injection method,and the luminescence wavelength was tuned in the range of 410-520 nm by changing the synthesis parameters.S ystematic characterization tests were performed on the synthesized samples,and three cubic phases of C sPbCl3,CsPbCl2Br and C sPbB r3 quantum dots were obtained experimentally,in which the luminescence wavelength of C sPbC 13 quantum dots was 403 nm and the half-peak width was 12.88 nm;the luminescence wavelength of C sPbCl2B r quantum dots was 478 nm and the half-peak width was 15.61 nm.The luminescence wavelength of C sPbB r3 quantum dots is 513 nm and the half-peak width is 15.17 nm.B y measuring the time-resolved photoluminescence spectra of quantum dot films spin-coated on silicon and quartz substrates,it was found that the exciton complexation rate of perovskite quantum dots on silicon substrates increased by more than six times,indicating the existence of fast-state NRET processes in the perovskite quantum dot-silicon hybrid structure.2.Using Al2O3 as the spacer layer between chalcogenide quantum dots and silicon substrate,the dependence of parameters such as quantum dot size,luminescence wavelength,spacer layer thickness and substrate refractive index on quantum dot photoluminescence lifetime in the hybrid structure is established and calculated by theoretical model and compared with experimental test results.The results show that when the thickness of the spacer layer is less than 20 nm,the experimental results are in good agreement with the theoretical results,indicating that the non-radiative energy transfer process in the chalcogenide quantum dot-silicon hybrid structure dominates;On the contrary,when the thickness of the spacer layer exceeds 20 nm,the experimental results are significantly smaller than the theoretical results,indicating that the radiative hybrid dominates,T hrough theoretical calculations and experimental measurements to analyze the N R E T process of different components of perovskite quantum dot-silicon based hybrid structures,the results show that the CsPbBr3 quantum dot-silicon hybrid structure obtained the NRET process with the highest quantum yield of 86.8%.3.A hybrid structure based on CsPbBr3 quantum dots-silicon nanowires（CsPbBr3 QDs-SiNWs）was designed,based on which a prototype Al/SiNWs@Al2O3/CsPbBr3 QDs/Spiro-OMeTAD/Ag Schottky junction solar cell device was constructed,utilizing the CsPbBr3 QDs-Si NWs NRET process in the hybrid structure can effectively reduce the charge loss due to defect states trapping when photogenerated carriers passing through the interface,thus improving the carrier collection efficiency.C ompared with the reference device without the addition of C sPbB r3 quantum dots,the short-circuit current density of the solar cell based on the hybrid structure of CsPbBr3 QDs-Si NWs was increased from 25.90 mA/cm2 to 33 23 mA/cm2,and the power conversion efficiency was increased from 9.88%to 11.70%.