Ultrahigh-radiance TTA-based OLED with 13 kA cm^-2 current injection

Area of Science:

• Organic electronics
• Optoelectronics
• Laser technology

Background:

• Organic semiconductors offer tunable properties and simple fabrication for devices like displays and solar cells.
• Electrically pumped organic lasers face challenges due to low charge mobility, gain quenching from carriers and triplets, and optical losses in device components.
• Existing organic light-emitting diodes (OLEDs) struggle to meet the high current densities required for efficient electrical pumping.

Purpose of the Study:

• To overcome the limitations hindering the fabrication of efficient electrically pumped organic lasers.
• To develop an OLED capable of sustaining high current densities and achieving population inversion for laser applications.
• To integrate OLED technology with advanced microcavity structures for enhanced light emission.

Main Methods:

• Fabrication of an OLED incorporating triplet-triplet annihilation (TTA) characteristics for improved electrical performance.
• Utilizing short-pulse electrical driving (15-ns) to minimize triplet accumulation and singlet-triplet annihilation (STA).
• Integration of the OLED with a high-quality distributed Bragg reflector (DBR) microcavity featuring ultrathin electrodes.

Main Results:

• The fabricated OLED achieved a current injection density of 13 kA/cm² under short-pulse driving.
• The device maintained nearly 1% external quantum efficiency (EQE) at 1 kA/cm² current injection.
• A record-high output power of 56 W/cm² was achieved, sustaining population inversion.
• Narrow-band light emission with a spectral linewidth of 5.5 nm was observed at 13 kA/cm² current injection.

Conclusions:

• The developed OLED technology effectively addresses key challenges in organic laser fabrication, including current injection and gain characteristics.
• The combination of TTA, short-pulse driving, and DBR microcavities enables high performance in organic optoelectronic devices.
• This research provides a significant advancement towards the realization of practical organic electrically pumped lasers.