Research on the quantum confinement effect and enhanced luminescence of red-emitting P5+-doped CaAl12O19:Mn4+,Mg2+ phosphors

Abstract

Mn⁴⁺-activated oxide red phosphors are always a hot topic in the luminescent material field to solve the lack of red light components in white-light-emitting diodes (WLEDs). Herein, a series of novel deep red-emitting CaAl_12−mP_mO_19+m:0.01Mn⁴⁺,0.2Mg²⁺ (m = 0–0.15) phosphors were synthesized and their crystal structure, luminescence properties and thermal stability were investigated in detail. The high-valence P⁵⁺ is used to replace low-valence Al³⁺ in the luminescent host CaAl₁₂O₁₉ to improve the photoluminescence quantum yield (PLQY) of phosphors. The doping of P⁵⁺ does not change the crystal phase structure of phosphors, and the luminescence intensity and PLQY are significantly enhanced. The analysis of the photocurrent and fluorescence lifetime shows that an electron trap with a quantum-confinement structure is formed in the phosphor host, which plays a key role in buffering photogenerated electrons. Therefore, the PLQY of the P⁵⁺-doped CaAl_11.90P_0.1O_19.10:0.01Mn⁴⁺,0.2Mg²⁺ phosphor increased from 9.8% (P⁵⁺-undoped) to 70.2%, and the mechanism of PLQY enhancement is proposed based on the analysis of the crystal structure. Furthermore, the phosphor has superior thermal stability and color purity (96.8%). Overall, this work provides new insights and ideas on quantum confinement effects for improving the quantum yield of Mn⁴⁺-activated luminescent materials.