Increasing the Stability of Deep Blue Phosphor-Sensitized OLEDs Using the Polariton-Enhanced Purcell Effect

Area of Science:

• Organic electronics
• Materials science
• Photophysics

Background:

• Deep blue organic light-emitting diodes (OLEDs) face stability challenges due to non-radiative triplet exciton annihilation.
• Phosphor-sensitized fluorescence (PSF) offers efficient deep blue emission but requires stability enhancement.
• The polariton-enhanced Purcell (PEP) effect has shown potential in increasing phosphorescent OLED lifetime.

Purpose of the Study:

• To investigate the application of the polariton-enhanced Purcell (PEP) effect for enhancing the stability of phosphor-sensitized fluorescence (PSF)-OLEDs.
• To reduce triplet annihilation events and improve the operational lifetime of deep blue OLEDs.
• To explore the impact of PEP on radiative decay rates and energy transfer dynamics in PSF-OLEDs.

Main Methods:

• Integration of a PEP cavity into PSF-OLED device architecture.
• Utilizing a platinum-complex phosphor sensitizer and a multi-resonance fluorescent emitter.
• Characterization of device performance, including lifetime, external quantum efficiency (EQE), and color coordinates.

Main Results:

• A 3.1-fold increase in device lifetime was achieved at a current density of 10 mA cm⁻².
• Reduced EQE roll-off and deep blue emission with CIE coordinates (0.13, 0.09) were observed.
• The PEP effect was found to increase radiative decay rates, suppressing triplet annihilation.

Conclusions:

• The PEP effect significantly enhances the stability and performance of deep blue PSF-OLEDs.
• PEP maximally extends lifetimes in devices with high triplet-to-singlet energy transfer rates.
• The benefits of the PEP effect are applicable to all triplet-based OLED technologies.