Preparation And Property Characterization Of The Perovskite ?CH₃NH₃?_xCs_1-xPbBr₃ Films By Sol-gel Method

Variety of the perovskite?CH₃NH₃?_x Cs_1-xPbBr₃ films were fabricated by the sol-gel method,and the microstructure and optical properties of the films were adjusted by varying the experimental parameters such as colloid solution concentration,soaking temperature,soaking time,gum solidification temperature,R_mol[MABr:CsBr].Effect of the parameters above was also intensively studied on the microstructure and the optical properties of the films.In addition,the thermal stability of the films,in particular,was studied.The main results were listed below:?1?The perovskite CH₃NH₃PbBr₃ films with<100>preferred orientation were fabricated and the thermal stability and mechanism for the thermal decomposition were studied as well.The critical temperature value for the thermal decomposition of the CH₃NH₃PbBr₃ film is 130oC,while the temperature for the complete decomposition to PbBr₂ is 170oC.The complete substitution of ions I^-by ions Br^-do not improve the thermal stability of the films.The microstructure and optical properties are closely related to the production of PbBr₂ and the introduction of defects in the process of the thermal decomposition.?2?The microstructure and the optical properties of the perovskite CH₃NH₃PbBr₃ films were adjusted by varing PbBr₂ sol solution concentration,MABr sol solution concentration and soaking time.Mechanism for the effect of these parameters on the microstructure and optical properties of the films was proposed as well after the analysis of the experimental data.?3?The<200>-oriented perovskite CsPbBr₃ films were fabricated.The monitoring of the microstructure and the optical properties of the perovskite CsPbBr₃films was done by varing the soaking temperature,soaking time and gum solidification temperature.The absorption edge clearly blue shifts and the stability is greatly improved for the CsPbBr₃ film compared with perovskite CH₃NH₃PbI₃ film.It is difficult to completely remove the residuals on the substrate and suppress the production of the by-products for the fabrication of the CsPbBr₃ films by soaking method alone.The increase in gum solidification temperature is helpful to fabricate pure CsPbBr₃ film and increase the fluorescence lifetime of the film.?4?The perovskite?CH₃NH₃?_xCs_1-xPbBr₃ films were fabricated and the monitoring of the films done.The introduction of ions MA⁺can greatly improve the surface morphology and the crystallization of the films.The optical band gap energy of?CH₃NH₃?_x Cs_1-x-x PbBr₃ films can be adjusted in the range of 2.19-2.32 eV by changing the R_mol[MABr:Cs Br].The fluorescence lifetime and luminescence intensity of the?CH₃NH₃?_xCs_1-xPbBr₃ film are significantly increased compared with CsPbBr₃films,while the thermal stability and the luminescence intensity of the?CH₃NH₃?_x Cs_1-xPbBr₃ film are also greatly increased compared with traditional perovskite CH₃NH₃PbI₃ film.