| All-inorganic metal halide perovskite CsPbX3（X=Cl,Br,I）have excellent optical and electrical properties,such as high photoluminescence quantum yield,tunable band gap and high carrier mobility,etc.,which show potential application prospects in the fields of light-emitting diodes,photodetectors and micro-nano lasers.Although a lot of works were carried out on the field of CsPbX3 lasers and light-emitting devices,the basic photoluminescence mechanism of CsPbX3 materials still needs to be studied.How to further improve the photoluminescence properties of CsPbX3 materials is also an urgent problem to be solved.In this thesis,two effective strategies are proposed to enhance the photoluminescent properties of TFA-derived CsPbBr3 film,and one of them is extended to the CsPbX3quantum dot system.The basic photoluminescence mechanism and carrier dynamics property of the sample with and without PL enhancement are studied.The results are as follows:（1）Uniform TFA-CsPbBr3 perovskite thin film with improved crystallization quality and enhanced photoluminescence intensity was obtained by adding anti-solvent chlorobenzene in the spin-coating process.The temperature-dependent photoluminescence spectra of TFA-CsPbBr3 thin film show an evolution from two emission peaks（free exciton,bound exciton）to single emission peak（bound exciton）due to the thermal quenching of free excitons emission at high temperature.The temperature-dependent time-resolved photoluminescence spectra show elongated PL lifetimes with the increase of temperature because of the dissociation effect of excitons.An unusual photoluminescence center shift with decay time was observed due to the exciton-exciton scattering and Burstein-Moss（B-M）effect,which was further proved by transient absorption spectra.（2）The photoluminescence enhancement is achieved by combining the TFA-CsPbBr3film and the Si O2/Ag film.Since the Purcell effect and F?rster energy transfer can both regulate the photoluminescence enhancement effect,the enhancement coefficient has a great relationship with the thickness of the Si O2 dielectric layer.It is found that when the thickness is 20 nm,the enhancement factor reaches the maximum value（5.1）.The temperature-dependent photoluminescence results show that CsPbBr3/Si O2/Ag exhibits a greater red shift than CsPbBr3/Si O2 with the temperature decreasing,which indicates the PL peak position of CsPbBr3/Si O2/Ag is closer to the surface plasmon resonance wavelength.Therefore,surface plasmon-exciton coupling intensity increases,and the PL enhancement factor increases with the decrease of temperature.The time-resolved photoluminescence results show that the introduction of surface plasmon can effectively reduce the photoluminescence lifetime and increase the spontaneous emission recombination rate of perovskite.（3）The CsPbX3 perovskite quantum dots with the photoluminescence center wavelength covering the visible light range from 436 nm to 650 nm were prepared by thermal injection method and ion exchange method,and then the photoluminescence property of the CsPbBr3 quantum dot film were enhanced by coupling with Ag films heating at different temperatures.The Ag nanoparticles of different sizes are obtained by heating Ag films with different temperatures,and the photoluminescence properties of the CsPbBr3quantum dot film are enhanced by the Ag nanoparticles.When the heating temperature of Ag film is 200°C,the photoluminescence enhancement ratio of the quantum dot film achieves maximum（6.18）;the photoluminescence enhancement is accompanied by a slight red shift of the photoluminescence emission center,which is attributed to the changing the carrier distribution caused by localized surface plasmon（LSP）coupling.The relationship between the full width at half maxima（FWHM）and the temperature indicates that the LSP coupling will reduce the optical phonon energy of the system,thus reduce the non-radiative recombination of the system and enhance the photoluminescence properties of the sample. |
PDF Full Text Request