Ultralong Room Temperature Phosphorescence through Both Space Confinement and Long-Range Charge Migration

Area of Science:

• Materials Science
• Photophysics
• Organic Chemistry

Background:

• Room-temperature phosphorescence (RTP) is crucial for optoelectronic applications.
• Achieving ultralong RTP (URTP) by suppressing nonradiative decay in host-guest systems remains a significant challenge.
• Confined spaces in host materials are effective for enhancing RTP by minimizing energy loss.

Purpose of the Study:

• To develop a novel host-guest material exhibiting ultralong room-temperature phosphorescence (URTP).
• To investigate the mechanisms responsible for suppressing nonradiative decay and enhancing phosphorescence lifetime.
• To explore the potential applications of the synthesized URTP material in security fields.

Main Methods:

• One-step heat treatment to embed three coumarin derivatives into a boric acid host.
• Characterization of the resulting host-guest material's phosphorescence properties (afterglow, lifetime, quantum yield).
• Analysis of host-guest interactions and defect formation using spectroscopic and structural methods.

Main Results:

• Successfully synthesized a URTP material with an afterglow duration of up to 60 seconds.
• Achieved a phosphorescence lifetime of 1.59 seconds and a quantum yield of 18.14%.
• Demonstrated that the 3D boron oxide network and specific covalent/coordination bonds effectively suppress nonradiative transitions.
• Identified oxygen vacancy defects and charge-separated states facilitating long-range charge migration and recombination, leading to long-lived phosphorescence.

Conclusions:

• The developed boric acid-based host-guest system effectively suppresses nonradiative decay, enabling URTP.
• Physical and chemical confinement, along with defect engineering, are key to achieving long-lived phosphorescence.
• The URTP material shows promise for applications in information encryption and decryption within security systems.