AIEgen Configuration Transition and Aggregation Enable Dual Prompt Emission for Single-Component Nondoped White OLEDs

The dual emission (DE) feature in materials holds great potential to revolutionize the development of one-component system white organic light-emitting diodes (WOLEDs). However, the reported DE materials remain scarce owing to the formidable challenge of breaking Kasha's rule and managing the intricate energy/charge transfer processes. Herein, we have introduced a groundbreaking DE AIEgen, 2CzAn-TPE, which possesses a simple structure and undergoes Z-to-E isomerization and exhibits yellow and red fluorescence powders for pre- and post-sublimation, respectively. With relatively lower potential energy, Z-conformation ((Z)-1,2-diphenyl-1,2-bis(4-(10-(9-phenyl-9H-carbazol-3-yl)anthracen-9-yl)phenyl)ethene) of 2CzAn-TPE can be readily transformed into E-conformation ((E)-1,2-diphenyl-1,2-bis(4-(10-(9-phenyl-9H-carbazol-3-yl)anthracen-9-yl)phenyl)ethene) via vacuum sublimation. The utilization of X-ray diffraction and grazing-incidence-wide-angle X-ray scattering techniques confirms the structural transformation, while the crystallographic analysis reveals the establishment of numerous intermolecular CH center dot center dot center dot pi interactions between the tetraphenylethene (TPE) moiety and both the anthracene and carbazole units. This allows a densely packed molecular arrangement, thereby offering propitious conditions for excimer generation in the E-conformation aggregated state. By utilizing the sublimated 2CzAn-TPE as an emitter, a nondoped one-component WOLED was prepared, exhibiting an exceptionally high external quantum efficiency (EQE) of 5.0%, which represents one of the highest performances among all one-component WOLEDs. This research introduces a novel, simple, and efficient approach to realize highly efficient one-molecule WOLEDs. The E-/Z- isomerization of 2CzAn-TPE gives rise to a dual-emissive (DE) phenomenon, as evidenced by both experimental investigations and theoretical calculations. The DE behavior is attributed to excimer formation in the E-isomer. Significantly, the strong intermolecular CH center dot center dot center dot pi interactions in the E-isomer play a central role in the excimer formation. Consequently, nondoped white organic light-emitting devices (WOLEDs) based on 2CzAn-TPE exhibiting an exceptionally high external quantum efficiency (EQE) of 5.0%, which represents one of the highest performances among all one-component WOLEDs. image