Research On Stability Improvement And Applications Of Lead-halide Perovskite Quantum Dots

In recent years,halide perovskite materials have not only achieved unprecedented success in the photovoltaic field,but have also shown great potential in other optoelectronic devices.Among them,inorganic halide perovskite?CsPbX₃,X=Cl,Br,I?quantum dots?QDs?have fascinating optical characteristics such as high brightness,adjustable emission wavelength,high color purity,and high defect tolerance,which have attracted tremendous research interests in virtue of their great application potentials in the fields of low-cost light sources and displays.Despite the promising applications of perovskite materials in various fields,the lack of stability has become a huge obstacle to their commercial application.Therefore,how to enhance the material stability has become a research hotspot in recent years.In this work,we selected CsPbBr₃QDs as the research object.The CsPbBr₃QDs were synthesized by ligand-assisted reprecipitation and hot injection methods.Later,a coating strategy was adopted to improve its stability.The morphology,optical properties,and stability measurements of CsPbBr₃QDs against light,heat,and moisture/oxygen were systematically studied.According to the characteristics of the prepared materials,they were applied in the field of white light-emitting diodes?WLEDs?and anti-counterfeiting,respectively.The details are as follows:First,we successfully prepared the CsPbBr₃/SiO₂QDs composites through a simple sol-gel reaction by using tetramethoxysilane as a single molecule precursor of silica.The as-prepared CsPbBr₃/SiO₂QDs composites demonstrate a substantially improved stability against heat,light,and environment oxygen/moisture.Besides,a relatively narrower photoluminescence linewidth and a higher quantum yield were achieved compared with the fresh CsPbBr₃QDs.Further,the CsPbBr₃QDs/SiO₂composites were applied as the color-converting layer curing on blue LED for WLED applications.Finally,a high power efficiency of 63.5 lm/W was obtained and the light emission could be efficiently sustained over 13 h without any decay in a continuous current mode,demonstrating a remarkable operation stability.It can be anticipated that the excellent properties and facile processing technique will make perovskite QDs/SiO₂composites attractive for applications in optoelectronics and industrial exploitation.To more effectively improve the optical performance and stability of CsPbBr₃QDs,we performed a detailed study on the effects of dual coating of surfactant??-?-phosphatidylcholine,LP?and silica on the stability and emission of CsPbBr₃QDs.Because of the synergetic effect of surfactant and core/shell configuration,the resulting CsPbBr₃/LP/SiO₂QDs composites demonstrated a higher photoluminescence quantum yield?>90%?,a better color purity,and a significantly improved stability to heat,ultraviolet light,water and ambient oxygen.The stability of CsPbBr₃/LP/SiO₂QDs composites was obviously better than that of CsPbBr₃/SiO₂QDs composites.In addition,because the CsPbBr₃/LP/SiO₂QDs composite solution has the ink characteristics,as well as excellent fluorescence characteristics and stability.This provides basic conditions for anti-counterfeiting high-tech security inks.By the ink jet printing technology,we demonstrated that our CsPbBr₃/LP/SiO₂QDs composites could act as a smart concealed ink for information encryption and decryption.More importantly,the anti-counterfeiting effect could be efficiently sustained even though the paper with designable patterns was crudely treated by water soak,heating/cooling cycling,and continuous ultraviolet light switching?1500cycles?.The above results obtained provide effective strategies to improve emission efficiency and stability of perovskite QDs,thereby endued them in the anti-counterfeiting application potential.