Achieving trap-depth-tunable organic persistent luminescence through host energy-level engineering.

Area of Science:

• Materials Science
• Organic Electronics
• Photophysics

Background:

• Traps are critical for organic persistent luminescence (OPL) but controlling their depth is challenging.
• Existing methods lack precision in tuning trap characteristics without affecting OPL properties.

Purpose of the Study:

• To introduce a host energy-level engineering strategy for precise control of trap depth in OPL materials.
• To demonstrate the tunability of trap depth and its impact on luminescence and energy storage.

Main Methods:

• Host energy-level engineering to tune trap depth.
• Randall-Wilkins method for trap depth quantification (0.38–0.72 eV).
• Density functional theory (DFT) calculations for validation.

Main Results:

• Achieved tunable trap depth from 0.38 to 0.72 eV without altering emission wavelength.
• Developed a host-guest material (CPND@DPEPO) with a deep trap (~0.72 eV) exhibiting 27-hour deep-blue OPL.
• Demonstrated efficient energy storage for 14 days at room temperature.

Conclusions:

• Established a fundamental principle for designing organic materials with controllable trap depth.
• Developed a pixel-programmable information storage device using OPL materials in organic light-emitting diodes (OLEDs).
• Potential applications in night tracing, military communication, and biological imaging.