The Optical Performance Study Of CsPbX₃ Perovskite Nanocrystals In Glasses

All inorganic CsPbX₃（X=Cl,Br,I,Cl/Br or Br/I）perovskite nanocrystals（NCs）have great potential for photovoltaic and optoelectronic applications due to their excellent photo performance.However,its stability is very poor,and it is very sensitive to oxygen,humidity,temperature and light.So,it is difficult to adapt to the environment in which the device is applied.In order to improve the stability of CsPbX₃ perovskite nanocrystals,there are several kinds of the attempts.For example,the CsPbX₃nanocrystals are combined with mesoporous materials or organic polymers.In addition,the core-shell perovskite nanocrystals have also been tested.However,these nondense structures and the poor stability are not sufficient to protect perovskite nanocrystals from external environment.Due to the good thermal,mechanical,and chemical stabilities,glasses have been employed as the host for various active luminescent ions or nanocrystals.The CsPbX₃ perovskite nanocrystals have good long-term stability.However,the CsPbX₃ perovskite nanocrystals in glass have low photoluminescence quantum yield（PL QY）.And tunable PL ranges of CsPbX₃ perovskite nanocrystal–embedded glasses are narrow,which can’t extend the entire visible region.So,it is difficult to apply of optical devices.Therefore,it is still urgent to find proper glasses to achieve more flexible precipitation of CsPbX₃ nanocrystal–embedded glasses with higher PL QY and wider spectral tuning range.The basic knowledge of quantum dots and properties of CsPbX₃ perovskite materials were introduced as well as the research progress of CsPbX₃ perovskite nanocrystals in glass.In this paper,the CsPbX₃（X=Br,I,Cl/Br or Br/I）perovskite nanocrystals were prepared in boro-germanate glass with high PL QY and good stability.Works were done mainly as follows:（1）The boro-germanate glass was prepared by a conventional melting method,and the CsPbX₃（X=Br,I,Cl/Br or Br/I）perovskite nanocrystal was synthesized in the glass by a heat-treatment method.The PL peak of CsPbX₃（X=Br,I,Cl/Br or Br/I）perovskite nanocrystals in glass can be turned from 440 nm to 700 nm by controlling the heat-treatment conditions and the composition of glasses.The PL QY of CsPbBr₃nanocrystals in glass is about 80%,and the PL QYs of CsPb（Cl/Br）₃ nanocrystals and CsPb（Br/I）₃ nanocrystals in glass are about 20%.（2）The water resistance,temperature stability and photostability of the prepared CsPbX₃ perovskite nanocrystals in glass were studied.The integral PL intensity of the CsPbX₃ NCs in glass almost completely recovered during the heating-cooling in the range from room temperature to 200°C.when the excitation power densities were kept low,the PL intensities of CsPb（Cl/Br）₃（3.18 W/cm²）,CsPbBr₃（1.96 W/cm²）and CsPb（Br/I）₃（1.96 W/cm²）NCs in glasses also fully recovered.However,when the excitation power densities were high enough,the surface decomposition of CsPbX₃NCs was driven by the OH^-in the glasses and the heat induced by the laser irradiation.But the surface decomposition of CsPbX₃ NCs can be completely recovered through thermal.（3）With CsPbBr₃ NCs in glass slice as light converter,green LED with a luminous efficiency of¹20 lm/W and an external quantum efficiency of³0%was fabricated.With CsPbBr₃ NCs and CsPbBrI₂ NCs in glass slices as light converters,the white LEDs with a luminous efficiency of 50-60 lm/W and an external quantum efficiency of 20-25% can be realized.