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Non-Doped Blue AIEgen-Based OLED with EQE Approaching 10.3 .
Pengbo Han1, Chengwei Lin1, Erhan Xia1
1State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, Center for Aggregation-Induced Emission, South China University of Technology, Guangzhou, 510640, China.
Angewandte Chemie (International Ed. in English)
|September 5, 2023
Summary
New blue luminogens with aggregation-induced emission (AIE) overcome triplet exciton loss in organic light-emitting diodes (OLEDs). This design enhances device performance by managing high-lying triplet states for efficient light emission.
Area of Science:
- Materials Science
- Organic Electronics
- Photophysics
Background:
- Aggregation-induced emission (AIE) luminogens (AIEgens) offer high efficiency in non-doped blue organic light-emitting diodes (OLEDs).
- High internal conversion rates (kIC(Tn)) between triplet levels in AIEgens lead to significant triplet exciton loss, limiting OLED performance.
- Managing high-lying triplet states is crucial for improving AIEgen-based OLEDs.
Purpose of the Study:
- To design and synthesize a novel blue luminogen that mitigates triplet exciton loss.
- To investigate the impact of fused molecular structures on AIE properties and triplet dynamics.
- To enhance the performance of non-doped blue OLEDs using the developed luminogen.
Main Methods:
- Synthesis of a new blue luminogen, DPDPB-AC, by combining an AIEgen (TPB-AC) with a hot exciton/triplet-triplet annihilation (TTA) unit (DMPPP).
- Characterization of AIE properties, dipole orientation, and internal conversion rates (kIC(Tn)) of the synthesized luminogen.
- Fabrication and testing of non-doped OLEDs utilizing DPDPB-AC as the emitting layer, employing transient electroluminescence and steady-state dynamic analysis.
Main Results:
- DPDPB-AC exhibits AIE characteristics and horizontal dipole orientation, similar to TPB-AC, but with a reduced kIC(Tn).
- The DPDPB-AC based non-doped OLED achieved an external quantum efficiency of 10.3% and a brightness of 69311 cd/m2.
- Transient and steady-state analyses confirmed that both TTA and hot exciton processes contribute to the superior device performance.
Conclusions:
- The designed luminogen DPDPB-AC effectively suppresses triplet exciton loss through managed high-lying triplet states and TTA.
- The study demonstrates a successful strategy for developing efficient organic fluorophores for high-performance non-doped blue OLEDs.
- This work offers valuable insights into controlling triplet exciton dynamics for advanced optoelectronic applications.
