Lead halide perovskite nanocrystals(NCs)exhibit high photoluminescence quantum yield(PLQY),high defect tolerance,narrow half peak width,and wide luminous gamut,making them the ideal optoelectronic materials in numerou...Lead halide perovskite nanocrystals(NCs)exhibit high photoluminescence quantum yield(PLQY),high defect tolerance,narrow half peak width,and wide luminous gamut,making them the ideal optoelectronic materials in numerous fields.Nonetheless,their production still suffers from the limited productivity at the bench level.In this work,we fabricated CsPbX3(X=Cl,Br,I)NCs within droplet-based micro-reactors,where both the nucleation and growth processes could be precisely controlled inside 130-nL microdroplets.This provides a new paradigm for the large-scale synthesis of perovskite NCs with high PLQY.Compared with other synthetic methods,this method can increase the concentration of reactant precursors by 3±116 times,while lowering the ligand to reactant ratio to 2%±50%of the commonly used hot-injection method.By modulating the reaction temperature and residence time,the structure-function relationship between the morphology of NCs and PL properties was extensively investigated.The microfluidic-based process allows the flexible adjustment in the proportion of PbX2 precursors to achieve the fabrication of perovskite NCs whose luminescence range covers the entire visible spectrum(406±677 nm)within one reaction.Finally,perovskite NCs with different halide ions were encapsulated in polymethyl methacrylate to prepare a colored light-emitting diode strip.展开更多
Cesium lead halide perovskite nanocrystals(NCs)have attracted unprecedented attention owing to their compelling properties for optoelectronic applications.Compared with the classical hot-injection method,the roomtempe...Cesium lead halide perovskite nanocrystals(NCs)have attracted unprecedented attention owing to their compelling properties for optoelectronic applications.Compared with the classical hot-injection method,the roomtemperature(RT)synthetic strategy is more facile and tender,but it is hard to obtain stable CsPbI3 NCs and it usually uses polar solvents that sometimes reduce the stability and properties of NCs.Here,we reported a simple approach to synthesize highly efficient and stable CsPbI3 as well as other colortunable CsPbX3 NCs with high quantum efficiency at room temperature via an anion exchange at the water-oil interface,in which the as-synthesized pristine CsPbBr3 NCs in toluene were treated in aqueous solutions of HX(X=Cl,Br,and I)and protonated oleylamine(OAm)acted as a carrier.The synthesized CsPbI3 NCs had an emission at 680 nm and even showed excellent colloidal stability after being stored for 32 d.The high efficiency and stability of the obtained CsPbX3 NCs were ascribed to the facts that:(ⅰ)the polar reagents were almost removed from the surface of NCs;(ⅱ)the defect-related nonradiative recombination was suppressed efficiently by surface passivation.展开更多
Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from ...Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from cornea is prevented, warm tear is lay- ered across corneal surface and the vessels of the palpebral conjunctiva provide heat to anterior eye. In most of the thermal models in human eye that are found in literatures, effect of blinking is not included, simulation is carried out only in open eye. Thus, in this paper, thermal effects of blinking are investigated using one-dimensional finite element method in transient state case. The bio-heat transfer process is simulated during different blinking rates, lid closure and opening. The simulation is carried out using normal and extreme values of ambient temperatures, blood temperatures, evaporation rates, blood perfusion rates, and lens thermal conduetivities. Blinking is found to increase corneal and lens temperature by 1.29℃ and 0.78℃ respectively when compared to open eye. The results obtained from this model are useful in predicting temperature distribution in different laser eye surgeries, hyperthermia and cryosurgery treatment of eyelid carci- noma, choroidal melanoma and can be used for diagnosing temperature-related diseases.展开更多
基金financially supported by the National Natural Science Foundation of China (22025801, 21991101, and 21736006)。
文摘Lead halide perovskite nanocrystals(NCs)exhibit high photoluminescence quantum yield(PLQY),high defect tolerance,narrow half peak width,and wide luminous gamut,making them the ideal optoelectronic materials in numerous fields.Nonetheless,their production still suffers from the limited productivity at the bench level.In this work,we fabricated CsPbX3(X=Cl,Br,I)NCs within droplet-based micro-reactors,where both the nucleation and growth processes could be precisely controlled inside 130-nL microdroplets.This provides a new paradigm for the large-scale synthesis of perovskite NCs with high PLQY.Compared with other synthetic methods,this method can increase the concentration of reactant precursors by 3±116 times,while lowering the ligand to reactant ratio to 2%±50%of the commonly used hot-injection method.By modulating the reaction temperature and residence time,the structure-function relationship between the morphology of NCs and PL properties was extensively investigated.The microfluidic-based process allows the flexible adjustment in the proportion of PbX2 precursors to achieve the fabrication of perovskite NCs whose luminescence range covers the entire visible spectrum(406±677 nm)within one reaction.Finally,perovskite NCs with different halide ions were encapsulated in polymethyl methacrylate to prepare a colored light-emitting diode strip.
基金supported by the Natural Science Foundation of Fujian Province(2019J05041)the Education Foundation of Fujian Province(JAT170021)the“Double-First Class”Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University。
文摘Cesium lead halide perovskite nanocrystals(NCs)have attracted unprecedented attention owing to their compelling properties for optoelectronic applications.Compared with the classical hot-injection method,the roomtemperature(RT)synthetic strategy is more facile and tender,but it is hard to obtain stable CsPbI3 NCs and it usually uses polar solvents that sometimes reduce the stability and properties of NCs.Here,we reported a simple approach to synthesize highly efficient and stable CsPbI3 as well as other colortunable CsPbX3 NCs with high quantum efficiency at room temperature via an anion exchange at the water-oil interface,in which the as-synthesized pristine CsPbBr3 NCs in toluene were treated in aqueous solutions of HX(X=Cl,Br,and I)and protonated oleylamine(OAm)acted as a carrier.The synthesized CsPbI3 NCs had an emission at 680 nm and even showed excellent colloidal stability after being stored for 32 d.The high efficiency and stability of the obtained CsPbX3 NCs were ascribed to the facts that:(ⅰ)the polar reagents were almost removed from the surface of NCs;(ⅱ)the defect-related nonradiative recombination was suppressed efficiently by surface passivation.
文摘Blinking is regarded as the continuous interrupted eyelid closure or opening and its thermal effect will compromise between these two. During a blink, the heat loss via convection, radiation and tear evaporation from cornea is prevented, warm tear is lay- ered across corneal surface and the vessels of the palpebral conjunctiva provide heat to anterior eye. In most of the thermal models in human eye that are found in literatures, effect of blinking is not included, simulation is carried out only in open eye. Thus, in this paper, thermal effects of blinking are investigated using one-dimensional finite element method in transient state case. The bio-heat transfer process is simulated during different blinking rates, lid closure and opening. The simulation is carried out using normal and extreme values of ambient temperatures, blood temperatures, evaporation rates, blood perfusion rates, and lens thermal conduetivities. Blinking is found to increase corneal and lens temperature by 1.29℃ and 0.78℃ respectively when compared to open eye. The results obtained from this model are useful in predicting temperature distribution in different laser eye surgeries, hyperthermia and cryosurgery treatment of eyelid carci- noma, choroidal melanoma and can be used for diagnosing temperature-related diseases.
