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Aggregation-Induced Emission-Based Polymer Materials: Ratiometric Fluorescence Responses Controlled by Hydrostatic Pressure
摘要： Dual fluorescence materials that exhibit controllable ratiometric changes in response to various external stimuli have attracted much attention from the viewpoints of applied material science and sensing/imaging technologies in interfaces. In the present study, we found fluorescence polymers based on aggregation-induced emission (AIE) characters. The functional AIE polymers can be converted to ratiometric fluorophores upon electronic excitation, and subsequently, their optical/photophysical properties can also be regulated by hydrostatic pressure or isotropic mechanical force. The degree of substitution (DS) of AIE branches on the polymer backbone plays critical roles in influencing the pressure-induced ratiometric fluorescence responses. The present study provides significant guidelines for developing AIE-based smart applied materials to response in hydrostatic pressure.
关键词： fluorescence spectroscopy,excited-state behavior,polyethylene,hydrostatic pressure,aggregation-induced emission,luminescence materials
更新于2025-09-23 15:21:01
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Yellow/Orange-Emitting ABZn2Ga2O7:Bi3+ (A = Ca, Sr; B = Ba, Sr) Phosphors: Optical Temperature Sensing and WLED Applications
摘要： Recently, there is growing interest in developing Bi3+-activated luminescence materials for optoelectronic applications. Herein, new yellow/orange-emitting ABZn2Ga2O7:Bi3+ (ABZGO, A = Ca, Sr; B = Ba, Sr) phosphors with tunable optical properties are synthesized by alkaline earth cation substitution. When Sr2+ substitutes Ca2+ and Ba2+, the excitation wavelength has a red shift from 325 to 363 nm, matching well with the n-UV chips based WLEDs. CaBaZn2Ga2O7:0.01Bi3+ (CBZGO:0.01Bi3+) exhibits two evident emission peaks at 570 and 393 nm originating from the respective occupation of Ca and Ba sites by Bi3+ ions. The optical tuning of CBZGO:Bi3+ phosphor is achieved by changing Bi3+ doping content and excitation wavelength based on the selected site occupation. Differently, both SrBaZn2Ga2O7:0.01Bi3+ (SBZGO:0.01Bi3+) and Sr2Zn2Ga2O7:0.01Bi3+ (SZGO:0.01Bi3+) phosphors exhibit a single broad emission band, peaking at 600 and 577 nm, respectively. Two different Bi3+ sites are also verified respectively in SBZGO and SZGO hosts by the Gaussian fitting of the asymmetric PL spectra and lifetime analysis. The different luminescence behaviors of ABZGO:0.01Bi3+ phosphors should be ascribed to the synergistic effect of centroid shift, crystal-field splitting and Stokes shift. Moreover, the temperature-dependent PL spectra reveal that cation substitutions of Sr2+ for Ca2+ and Ba2+ can efficiently improve the thermal stability of ABZGO:0.01Bi3+ phosphors. In view of different thermal responses to various temperature for two emission peaks of CBZGO:0.01Bi3+ phosphor, an optical thermometer is designed and has a good relative sensitivity (Sr = 1.453% K-1) at 298 K. Finally, a WLED with CRI = 97.9 and CCT = 3932 K is obtained by combining SZGO:0.01Bi3+ and BAM:Eu2+ phosphors with a 370 nm n-UV chip, demonstrating that SZGO:0.01Bi3+ is an excellent yellow-orange-emitting phosphor for n-UV WLED devices. This work stimulates the exploration of optical tuning by cation substitution to obtain remarkable luminescence materials for optical temperature sensing and WLED applications.
关键词： optical temperature sensing,WLED applications,optical tuning,Bi3+-activated,thermal stability,luminescence materials
更新于2025-09-19 17:13:59