Achieving tunable long persistent luminescence in metal organic halides based on pyridine solvent

The research of long persistent luminescence(LPL)materials has yield brilliant results in many fields.However,the efforts are still needed for the regulation of the LPL performance.In this work,a series of LPL metal organic halides with rich halogen-bond interactions,Py-CdX_(2)(X=Cl,Br,I)were synthesized through self-assembly by Cd X_(2)and pyridine solvent.The steady-state emission redshifted and phosphorescence lifetime declined as the halogen atoms are aggravated.Three halides exhibit adjustable emission from blue to green and multiple phosphorescence from green to yellow at room temperature by changing the excitation wavelengths.Surprisingly,Py-CdX_(2)can emit the visible color-tunable LPL from green to yellow after removing different excitation sources at ambient conditions.Combing the results of theoretical calculation and experimental analysis,it is found that heavy atom effect and the rich intermolecular halogen bond help realize LPL and multiple triplet states originated from the pyridine ring and the halogens.

Studies on Self-Luminous Material and Coating with Long Persistent Yellow-Green Afterglow

The preparation, properties, expression and luminescent mechanism of self luminous material (SrAl 2O 4∶Eu 2+ , Dy 3+ ) were discussed. The long afterglow luminescent coating was prepared by adding proper luminescent powders SrAl 2O 4∶Eu 2+ , Dy 3+ and other aids into styrene/acrylic emulsion. The best prescription of the coating was defined. The properties of luminescent coating were determined. The primary factors which affect the coating properties were discussed.

A novel long persistent luminescent material CaGeO_(3):Tb^(3+)with photo-stimulation properties

A novel green long afterglow material CaGeO_(3):Tb^(3+)was synthesized by high temperature solid phase method.According to the experimental results,CaGeO_(3):Tb^(3+)is a green long persistent luminescent(LPL)material with excellent performance.CaGeO_(3):Tb^(3+)shows LPL emission peak at 442,490.9,548.7,588.5 and 623.8 nm,corresponding to ^(5)D_(3) to^(7)F_(4)and^(5)D_(4)to^(7)F_(J)(J=6,5,4,3)transitions of Tb^(3+).Its CIE coordinates are(0.27,0.50),indicating that the afterglow emission is close to the light of green region.In addition,after the excitation source is turned off,the afterglow time is longer than 90 min.After an interval of 7 h,the photo-stimulation luminescence(PSL)can be observed by using 980 nm laser cyclic excitation.The thermoluminescence(ThL)results show that there are three types of traps in the material and their depths are 0.666,0.774 and 0.892 eV respectively,which are caused by the doping of Tb^(3+).All the results show that CaGeO_(3):Tb^(3+)is an excellent long afterglow luminescent material.

Thermally stable photoluminescence and long persistent luminescence of Ca3Ga4O9:Tb^3+/Zn^2+

A green long persistent luminescence（LPL） phosphor Ca3Ga4O9：Tb3＋/Zn2＋ was prepared. Ca3 Ga4 O9 matrix exhibits blue self-activated LPL due to the creation of intrinsic traps. When Tb3＋ is doped, the photoluminescence（PL） and LPL colors change from blue to green with their intensities significantly enhanced. The doping of Zn^（2＋） evidently improves the PL and LPL performances of the Ca3Ga4O9 matrix and Ca3Ga4O9：Tb^（3＋）. The thermoluminescence（TL） spectra show that a successive trap distribution is formed by multiple intrinsic traps with different depths in the Ca3 Ga4 O9 matrix, and the incorporation of Tb^（3＋） and Zn^（2＋） effectively increases the densities of these intrinsic traps. The existence of a successive trap distribution makes the Ca3 Ga4 O9：Tb^（3＋）/Zn^（2＋） phosphor exhibit thermally stable PL and LPL, It is indicated that this phosphor shows great promise for the application such as high-temperature LPL phosphor.

A NIR to NIR rechargeable long persistent luminescence phosphor Ca_(2)Ga_(2)GeO_(7):Yb^(3+),Tb^(3+)

Near infrared to near infrared(NIR-NIR)photo-stimulated persistent luminescence(PSPL)has shown excellent potential in high-resolution bioimaging for deep tissues.However,the PSPL in NIR-Ⅱregion(900-1700 nm)is still lacking.In this work,Ca_(2)Ga_(2)GeO_(7):Yb^(3+),Tb^(3+)(CGGYT)phosphor with unique lowdimensional crystal structure was synthesized by high-temperature solid-state reaction.Thanks to the carriers transferring from deep traps to shallow ones induced by low energy light,the 978 nm PSPL originating from ^(2)F_(5/2) to ^(2)F_(7/2) transition of Yb^(3+)induced by multimode stimulating(980 nm or WLED)is successfully realized after pre-excited by UV lamp.The NIR PSPL of the specimen can be repeatedly stimulated after placed in dark for 12 h.Moreover,the results indicate that codoping with Tb^(3+)can significantly enhance the NIR-ⅡPSPL owing to the quantum cutting persistent energy transfer(QC PET)from Tb^(3+)to Yb^(3+).Our study points to a new direction for the future development of multimode PSPL materials for bioimaging or multimode optical storage applications.

开发稳定有机阴离子自由基实现可应用于余辉照明的长持续发光

稳定阴离子自由基的开发在获得高效激基复合物有机超长持续发光材料体系中起到重要作用,但仍然是一个艰巨的挑战.有鉴于此,我们通过提高阴离子自由基的稳定性和降低激基复合物中电荷分离后形成的自由基中间体的再复合速率来开发高效的激基复合物有机长持续发光.我们所开发的激基复合物体系展现出了优异的绿色长持续发光,发光持续时间超过了180分钟.时间分辨的电子顺磁共振测试证实了超长持续发光的获得是因为开发的受体能形成稳定的阴离子自由基和低的自由基阴阳离子再复合速率.将我们所开发的材料应用到发光二极管中,能够制备出智能余辉照明器件.当关闭余辉照明器件的电压180秒后,纸上的英文单词还能被照亮并辨识出来.当前的工作不仅为开发受体材料来实现高效的激基复合物有机长持续发光提供了重要借鉴,也为有机长持续发光在节能余辉照明领域的应用开辟了道路.