Study On Optical Property Regulation Of Metal Halide And Its Application In Luminescent Solar Concentrator

Luminescent solar concentrator（LSC）is a waveguide device used to concentrate solar radiation for energy exchange.Fluorescent materials absorb sunlight and convert it into fluorescence.Fluorescence is fully reflected in the waveguide medium and can be guided to the edge of the LSC.Solar cells are coupled at the edge of the LSC,which converts concentrated fluorescence into electrical energy.Since the transverse area of LSC is larger than the edge,the use of expensive PV materials is reduced.Luminescent solar concentrators based on colloidal nanocrystals（NCs）are the key components of integrated photovoltaic（BIPV）.However,the strong reabsorption effect or expensive and toxic components contained in NC hinder their application.However,the strong reabsorption effect or expensive components contained in NC hinder their application.Meanwhile,the scattering of nanocrystals in LSC has been neglected.In this study,CsPbBr₃ perovskite nanoparticles and Cs₃Cu₂X₅（X=I,Cl）metal halides were prepared by thermal injection method.The two metal halides were optically regulated by adjusting the reaction temperature and metal halide elements.LSC was prepared by spinning the two materials on polydimethylsiloxane（PDMS）or mixing with polydimethylsiloxane uniformly.The two materials were characterized by transmission electron microscopy and X-ray diffraction.The optical properties were analyzed by UV-visible absorption spectrum,steady-state photoluminescence spectrum and time-resolved fluorescence spectrum.The transmittance of LSC was measured by transmission spectrum,and the photoelectric performance was tested by UV photoelectric response and AM 1.5G(100 mw cm^-2)simulated solar light source test system.In this work,the influence of scattering on the performance of LSC is deeply studied,which has important guiding significance for the influence of scattering on the photoelectric performance of LSC system of other NC fluorescent materials.The research of this paper mainly includes the following aspects:（1）The optical band gap of CsPbBr₃ metal halide material is regulated by reaction temperature.It is found that the quantum confinement effect is an important reason for the blue shift of luminescence with the decrease of reaction temperature.The obtained CsPbBr₃ NCs were encapsulated in PDMS matrix,and their samples still maintained their optical properties and showed long-term air and water stability.LSC was prepared by uniformly spin coating the sample on PDMS with CsPbBr₃ nanoparticles as fluorescent material.Through the photoelectric performance test,the PCE of CsPbBr₃ NCs LSC is 2.5%,and LSC shows photoelectric response in the absorption range of CsPbBr₃ NCs.（2）The optical properties are regulated by changing the halogen atoms in Cs₃Cu₂X₅（X=I,Cl）.Through testing,it is found that it has excellent optical properties.This material has efficient self trapping exciton emission and large Stokes displacement.Low cost and non-toxic LSC was prepared based on Cs₃Cu₂X₅（X=I,Cl）NCs,which showed obvious non reabsorption characteristics.The fluorescence spectra of Cs₃Cu₂X₅（X=I,Cl）NCs and LSC were measured by temperature variation and time-resolved fluorescence spectra.It was found that the fluorescence properties of NCs in PDMS still maintained.In different LSC device sizes,the edge efficiency is close to the theoretical limit（～70%）.In the edge efficiency of CsPbBr₃ of the comparison sample with reabsorption,there is obvious reabsorption at the short wavelength in LSC,and the higher the sample concentration,the more obvious the reabsorption.In addition,by the above LSC（8×8×0.5 cm³）and commercial polysilicon PV cells shows a power conversion efficiency（PCE）of up to 1.8%.In addition to the waveguide effect of LSC on luminescent photons,these excellent PCE have also been proved to be caused by the scattering of visible solar photons.These results clearly illustrate the photon propagation mechanism in LSC based on Cs₃Cu₂X₅ NC or similar colloidal NC.