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Interlocked Rotaxane Enables TADF with Distinct Excited-State Structural Relaxation
Chuan-Jing Lin1, Kai-Hsin Chang1, Chun-Yen Lin1
1Department of Chemistry, National Taiwan University, Taipei 106319, Taiwan.
Journal of the American Chemical Society
|January 29, 2026
Summary
We developed a novel rotaxane-based thermally activated delayed fluorescence (TADF) exciplex for organic light-emitting diodes (OLEDs). This mechanically interlocked molecule demonstrates efficient green electroluminescence and improved operational stability.
Area of Science:
- Materials Science
- Organic Chemistry
- Physical Chemistry
Background:
- Thermally activated delayed fluorescence (TADF) materials are crucial for high-efficiency organic light-emitting diodes (OLEDs).
- Exciplexes offer tunable electronic properties but often suffer from stability issues.
- Mechanically interlocked molecules (MIMs) provide unique structural control and enhanced stability.
Purpose of the Study:
- To demonstrate the first rotaxane-based TADF exciplex for OLED applications.
- To investigate the excited-state structural relaxation dynamics of the rotaxane exciplex.
- To evaluate the performance of the rotaxane exciplex in OLED devices.
Main Methods:
- Synthesis of a rotaxane exciplex (CT-Rotaxane) using a triazene cage host and a carbazole derivative guest.
- Characterization of TADF properties, including delayed fluorescence, singlet-triplet energy gap (ΔEST), and reverse intersystem crossing rate.
- Time-resolved spectroscopy to study structural relaxation in solution and solid states.
- Fabrication and testing of rotaxane-type OLEDs.
Main Results:
- The synthesized CT-Rotaxane exhibits TADF characteristics with microsecond-scale delayed fluorescence.
- Pronounced structural relaxation was observed in both solution (264 ps) and solid states (177 ns).
- Rotaxane-type OLEDs achieved a peak external quantum efficiency (EQE) of 7.23% with green electroluminescence.
- The rotaxane OLEDs outperformed nonrotaxane counterparts in efficiency and operational stability.
Conclusions:
- Mechanically interlocked TADF exciplexes represent a promising strategy for advanced optoelectronic devices.
- The unique structure of CT-Rotaxane leads to enhanced performance in OLEDs.
- Rotaxane architecture offers a pathway to improve both efficiency and stability in TADF materials.
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