宽带近红外荧光粉KScP_(2)O_(7)∶Cr^(3+)的发光特性研究及近红外LED器件应用

Luminescence Properties of KScP_(2)O_(7)∶Cr^(3+)Broadband Near-infrared Phosphor and Application of Near-infrared LED Device

近红外(NIR)器件的小型化和智能化需求推动了高效宽带近红外荧光粉的设计与发展。目前,Cr3+激活的宽带近红外荧光粉主要采用传统的多格位共占据策略设计实现。然而,由于处在不同晶体学格位的Cr3+热猝灭行为不一致和光谱稳定性差等问题,导致其实际应用受限。本文基于单格位占据策略,采用高温固相法制备了一系列宽带近红外荧光粉KSc1-xP_(2)O_(7)∶xCr^(3+)(x=0.01~0.09),并对其晶体结构、发光性能及热猝灭机理进行分析。研究结果表明,在x=0.03时,KSc_(0.97)PO_(7)∶0.03Cr^(3+)(KSP∶0.03Cr^(3+))样品发光强度达到最大值,随后出现浓度猝灭现象,该现象主要归因于相邻Cr^(3+)‐Cr^(3+)之间的能量传递。在蓝光激发下,KSP∶0.03Cr^(3+)样品光谱覆盖700~1200 nm,发射主峰位于857 nm,半高宽为149 nm。此外,通过晶体结构和低温光谱分析以及对Cr^(3+)所处晶体场强度计算,表明该宽带近红外发射的实现归因于Cr^(3+)占据处于弱晶体场(Dq/B=1.98)的Sc^(3+)晶体学格位。在高温373 K时,样品的发光强度为室温下发光强度的60.2%,表明该荧光粉具有良好的热稳定性。最后,利用该荧光粉与蓝光LED芯片制备了近红外荧光粉转换型LED(NIR pc‐LED)器件,证实该荧光粉在生物医学成像、夜视以及食品检测方面具有潜在应用价值。

The miniaturization and enhanced intelligence of near infrared(NIR)devices have stimulated the design and advancement of high-efficiency broadband NIR phosphors.It is widely believed that multisite co-occupancy strategy by Cr3+ions is a very effective method for designing broadband near-infrared phosphors.However,Cr3+ions at different crystallographic sites often exhibit distinct thermal-quenching behaviors,leading to poor spectral stability,which hampers their practical applications.In our work,we prepared a series of KSc1-xP_(2)O_(7)∶xCr^(3+)(x=0.01-0.09)broadband NIR phosphors via the high temperature solid-state method using the one-site occupation strategy.The crystal structure,luminescence performance and thermal quenching mechanism of KSc_(1-x)P_(2)O_(7)∶xCr^(3+)were investigated in detail.At x=0.03,the luminescence intensity of KSc_(0.97)P_(2)O_(7)∶0.03Cr^(3+)(KSP∶0.03Cr^(3+))reaches its maximum.The concentration quenching appears when x exceeds 0.03,which is attributable to energy transfer between adjacent Cr^(3+)-Cr^(3+).Under blue light excitation of~471 nm,the KSP∶0.03Cr^(3+)phosphor exhibits a broadband emis‐sion ranging from 700 nm to 1200 nm,with a peak centered at 857 nm and a full width at half-maximum(FWHM)of~149 nm.Structural analysis and low temperature spectroscopy indicate that the broadband NIR emission originate from Cr3+occupying a single Sc^(3+)site with the weak crystal field(Dq/B=1.98)in the KSP host.At 373 K,the inte‐grated emission intensity of KSP∶0.03Cr^(3+)sample keeps 60.2%of that at room temperature,suggesting good PL ther‐mal stability.Finally,we prepared a near-infrared phosphor-converted LED device(NIR pc-LED)by utilizing the KSP∶0.03Cr^(3+)NIR phosphor and a blue light LED chip,and confirm its potential applications in night vision,bio‐medical imaging,and food detection.