Zeolitic imidazolate framework glasses emit white light

TL;DR

This paper reports the discovery of broadband white light emission in Zn-based ZIF glasses, enhanced by annealing, leading to the creation of stable, efficient white LEDs with promising photonic applications.

Contribution

It introduces the first observation of white light emission in ZIF glasses and demonstrates their potential in LED technology through annealing techniques.

Findings

White light emission in Zn-based ZIF glasses can be enhanced by annealing.

Annealing causes a red shift in emission above a critical temperature.

Achieved a photoluminescence quantum yield of 12.2% in ZIF glass.

Abstract

Zeolitic imidazolate framework (ZIF) glasses represent a newly emerged class of melt-quenched glasses, characterized by their intrinsic nanoporous structure, good processability, and multifunctionalities such as gas separation and energy storage. However, creating photonic functionalities in Zn-based ZIF glasses remains elusive. Here we show a remarkable broadband white light-emitting behavior in a Zn-based ZIF glass, which can be enhanced by annealing. Furthermore, we discovered a sharp red shift upon increasing annealing temperature above the critical temperature of 1.07Tg, where Tg is the glass transition temperature, for a short duration of 30 min. Finally, we achieved a high absolute internal photoluminescence quantum yield of 12.2% upon annealing of ZIF glass at 1.13Tg. Based on the optimally annealed ZIF glass, we fabricated a white light-emitting diode (LED) with the luminous efficacy of 4.2 lm/W and high operational stability, retaining 74.1% of its initial luminous efficacy after 180 min of continuous operation. These results not only demonstrate the feasibility of utilizing ZIF glasses in LED applications but also mark a significant advancement in the development of durable, efficient, and multifunctional photonic materials.