IntroductionCsPbBr₃ perovskite quantum dots are considered as excellent green light materials in the field of wide color gamut displays due to their excellent luminescence characteristics, such as high photoluminescence quantum yield (PLQY) and narrow full width at half maximum (FWHM). However, CsPbBr₃ quantum dots irreversibly deteriorate when exposed to oxygen, water, light and heat due to their low formation energy and strong ionic properties, which restricts their application. The preparation of CsPbBr₃ quantum dots via in-situ crystallization in glass is considered as one of the effective strategies to improve their stability. In this study, borosilicate glass was used as a matrix to investigate the effect of Sc₂O₃ introduction on the glass network structure and the regulatory effect on the crystallization behavior and luminescence performance of CsPbBr₃. In addition, the photostability and thermostability of the samples were analyzed. CsPbBr₃ quantum dot glass powder with the high quantum efficiency and narrow FWHM could be used to prepare white LED with a high luminous efficiency and a wide color gamut.MethodsA series of CsPbBr₃ quantum dot glasses were prepared by a conventional melt quenching-heat treatment method. The specific molar composition ratio of the glass was 42B₂O₃-20SiO₂-4Li₂O-8ZnO-3MgO-3Cs₂O-6PbBr₂-6NaBr-xSc₂O₃ (mole fraction, x = 0, 0.1, 0.3, 0.5, and 0.7). According to the composition of each glass stoichiometric ratio, the raw materials were weighed, and fully ground in a mortar for 30 min. The mixed powder was then transferred to a corundum crucible and placed in a high-temperature muffle furnace at 1200 ℃ for 15 min. Subsequently, the melt was poured into a preheated graphite mold and annealed for 3 h to relieve thermal stress. After cooling to room temperature, a transparent precursor glass (referred to as PG) was obtained. CsPbBr₃ quantum dot glass was obtained via heat treatment of precursor glass samples at different temperatures (i.e., 460, 470, 480, 490 ℃, and 500 ℃) for 10 h. Finally, the prepared CsPbBr₃ quantum dot glass was cut, polished or ground into a powder for further characterization and use.Results and discussionThe results show that the average particle size of CsPbBr₃ quantum dots gradually decreases from 13.22 nm to 3.42 nm as the amount of Sc₂O₃ introduced increases. This indicates that the introduction of Sc₂O₃ can alter the glass network structure under identical external conditions, which in turn affects the particle size of the quantum dots. Note that the peak intensity of the [PbBr₆]^4- firstly increases and then decreases with increasing the amount of Sc₂O₃ introduced. The peak intensity of [BO₃]/[SiO₄] gradually decreases. This is primarily attributed to the Sc₂O₃ additive, which reduces the [BO₃] content within the network structure, strengthens the glass network, and affects the crystallization behavior of the quantum dots.The obtained samples exhibit a typical narrow-band luminescence. Under the same amount of Sc₂O₃ introduced, PL spectra of CsPbBr₃ quantum dot glass samples heat-treated at different temperatures show that the luminescence intensity firstly increases and then decreases with the increase of the temperature, and a phenomenon is attributed to fluorescence quenching. The long lifetime is reduced by 20 ns, but the proportion of long-lived emission gradually is increased as the amount of Sc₂O₃ introduction is increased. This is due to the improvement of the surface quality of the quantum dot, indicating that carrier quenching can be effectively minimized. Also, the the internal and external photoluminescence quantum yields of the optimal CsPbBr₃ quantum dot glass samples are 62.98% and 37.92% at 460 nm excitation. Moreover, they can maintain 64.51% of the original luminescence intensity after continuous illumination upon a 455 nm blue LED chip (20 V, 20 mA) for a week, laying a foundation for developing high-brightness LED devices. After three cycles of heating and cooling (at 298-473 K), the luminescence intensity of the optimal sample can gradually return to the initial value, and the peak emission wavelength and FWHM also show obvious temperature dependence and excellent recovery ability, indicating that the CsPbBr₃ quantum dot glass has a good luminescence thermal stability.ConclusionsCsPbBr₃ perovskite quantum dots with different amounts of Sc₂O₃ were precipitated in a borosilicate glass matrix by a conventional melt quenching-heat treatment method. Under the same heat treatment conditions, the structure of the glass network improved and became dense, as well as the average size of the quantum dots decreased from 13.22 nm to 3.42 nm with the increase of the amount of Sc₂O₃ introduced. After optimization, the internal and external photoluminescence quantum yields of the optimal CsPbBr₃ quantum dot glass samples were 62.98% and 37.92% at 460 nm excitation. The denser network structure effectively isolated the quantum dots from air, water, and oxygen erosion, significantly reducing phase separation and degradation caused by external environmental factors, thus having a good thermal cycle recovery. For the white LED prepared with the superior luminescent properties of the CsPbBr₃ quantum dot glass powder, the color coordinates were located at (0.3135, 0.3077), the correlated color temperature was 6647 K, and the color gamut reached 130.95% of the NTSC standard and 97.90% of the Rec. 2020 standard, indicating a potential application in the backlight display field.