Structural evolution of organic–inorganic hybrid crystals for high colour-rendering white LEDs

Abstract

Luminescent crystals with high efficiency have huge potential in applications for white light-emitting diodes (LEDs). Herein, organic–inorganic hybrid crystals doped with Mn⁴⁺, [N(CH₃)₄]₂XF₆:Mn⁴⁺ (X = Si, Ge, and Ti), were grown under mild conditions. Their crystal structural evolution was confirmed by single-crystal X-ray diffraction at different temperatures. These crystals exhibit intense red emission with a high external quantum efficiency (73.0% for [N(CH₃)₄]₂TiF₆:Mn⁴⁺) and good thermal stability. The warm white LEDs were fabricated by combining these red-emitting phosphors with a YAG:Ce³⁺ ceramic chip. As-grown crystals can significantly optimize the performances of white LEDs (colour rendering index up to 95). Hence, this work provides a new strategy to explore Mn⁴⁺-activated organic–inorganic hybrid materials for white LEDs.