Lead-free MnII-based red-emitting hybrid halide (CH6N3)2MnCl4 toward high performance warm WLEDs

Abstract

Environmentally friendly metal hybrid halides show great promise for white light emitting diode (WLED) applications due to their unique optical properties. Herein, a lead-free blue-light excited red-emitting Mn²⁺-based hybrid halide (CH₆N₃)₂MnCl₄ was obtained via a facile mechanochemical method. (CH₆N₃)₂MnCl₄ with octahedrally coordinated Mn²⁺ ions exhibits intense red emission at 650 nm with a high photoluminescence quantum yield (PLQY) of 55.9% benefiting from its unique crystal structure of ferromagnetic (FM) coupled trimeric [Mn₃Cl₁₂]⁶⁻ linear chains. Besides, (CH₆N₃)₂MnCl₄ also possesses excellent thermal stability on account of the relatively weak electron–phonon coupling effect. Moreover, the luminescence intensity of (CH₆N₃)₂MnCl₄ can be significantly improved by 8% Zn²⁺ alloying. The WLEDs with different correlated color temperatures (CCT) fabricated using (CH₆N₃)₂MnCl₄:8%Zn²⁺ and the yellow phosphor Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce³⁺) using a blue LED chip exhibit much better overall electroluminescence performance than those based on (CH₆N₃)₂MnCl₄. A warm WLED with a CCT of 3984 K, a high luminous efficacy of 90.41 lm W⁻¹ and a color rendering index (CRI) of 93.7 was obtained based on the modified (CH₆N₃)₂MnCl₄:8% Zn²⁺ halide, indicating its high potential as a red-emitting component for WLED applications.