Spectral design in Cr3+-doped NIR phosphors via crystal field modulation

Abstract

Effective broadband longer-waved (>850 nm) near-infrared (NIR) phosphors are in great demand for diverse applications. Benefitting from photoluminescence tuning of Cr3+-activated phosphor, a sequence of LaSc3-2xCaxSixB4O12(LSCSB): Cr3+ (0 ≤ x ≤ 1.0) phosphors have been designed via regulating the crystal field environment based on non-equivalent co-substitution of Sc3+-Sc3+ by Ca2+-Si4+. The relationship between structural variation, crystal field modulation, luminescence performance, and thermal stability of the LSCSB: Cr3+ (0 ≤ x ≤ 1.0) have been investigated. The structural evolution is induced along with x value, consequently, the phosphors exhibit a tunable emission wavelength toward longer wavelength from 871 nm to 880 nm depending on crystal field engineering, which enriches the NIR phosphor with a longer emission wavelength. Moreover, the photoluminescence behaviors of LSCSB: yCr3+ (x = 0.9) (0.01 ≤ y ≤ 0.13) have been studied in detail. Targeted phosphor LSCSB: 0.09Cr3+ (x = 0.9), with enhanced emission intensity and thermal stability compared with that of LSB: Cr3+, yields a broadband NIR emission centered at 880 nm under 460 nm excitation. The NIR pc-LED, fabricated by combining the LSCSB: 0.09Cr3+ (x = 0.9) with a blue LED chip, exhibits excellent thermal stability and reliability in the practical application process, indicating its potential for the application in blue-pumped NIR pc-LED towards diversified applications. In addition, a consequence of regular pattern has been summarized to provide an efficient approach to design and modulate the Cr3+-doped phosphor with proper luminescence property.