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Anomalous current-dependent ISC modulated by cascade energy transfer among multiple excited states in exciplex-based
Jiang Chen1, Xiangwen Tan1, Rongxing Cao1
1Key Laboratory of Optoelectronic Engineering, College of Physics and Electronic Engineering, Chongqing Normal University Chongqing 401331 People's Republic of China niulb03@126.com.
RSC Advances
|July 28, 2026
Summary
Magneto-conductance measurements reveal how spin dynamics in organic light-emitting diodes (OLEDs) depend on excited states. Device performance is linked to carrier balance and energy transfer, offering insights for OLED design.
Area of Science:
- Organic electronics
- Solid-state physics
- Photophysics
Background:
- Exciplex systems are crucial for high-efficiency organic light-emitting diodes (OLEDs).
- The spin dynamics of multiple coexisting excited states in these systems remain poorly understood.
- Understanding these mechanisms is key to optimizing OLED performance.
Purpose of the Study:
- To investigate the microscopic spin dynamic mechanisms in OLEDs with coexisting exciplex and electromer states.
- To explore the influence of carrier distribution and Dexter energy transfer (DET) on magneto-conductance (MC) responses.
- To provide insights for the rational design and optimization of exciplex-based OLEDs.
Main Methods:
- Utilized magneto-conductance (MC) measurements at various temperatures and current (I) levels.
- Compared two devices with different acceptors (TmPyPB vs. PO-T2T) using TAPC as the donor.
- Analyzed the interplay between intersystem crossing (ISC), reverse intersystem crossing (RISC), and Dexter energy transfer (DET).
Main Results:
- Device 1 (TmPyPB acceptor) showed unsatisfactory performance and abnormal current-dependent MC response due to imbalanced carriers.
- Device 2 (PO-T2T acceptor) exhibited excellent performance and regular current-dependent MC response.
- Device 1's behavior was modulated by temperature and doping ratio, influencing DET strength and CT-RISC intensity.
Conclusions:
- Imbalanced carrier distribution significantly impacts spin dynamics and energy transfer in exciplex OLEDs.
- Dexter energy transfer plays a critical role in modulating the current-dependence of MC responses.
- Controlling energy transfer channels offers a pathway for designing and optimizing high-performance OLEDs.
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