Achieving Multi-Color Emissive Organic Light-Emitting Diodes With Single-Component Molecule Through Conformational Regulation

Abstract

Purely organic single-component luminescent materials enabling multi-color photoluminescence are gaining significant interest, given their tunable optical properties, environmental friendliness, and cost-effectiveness. However, realizing multi-color electroluminescence from a single-component emitter for application in organic light-emitting diode (OLED) remains challenging, mainly due to the limitations in achieving distinct excited-state conformations in amorphous or solid states. In this study, we report two novel emitters (Bppy-PTZ and Bpph-PTZ) by incorporating a benzophenone acceptor and phenothiazine donor with pyridyl and phenyl π-bridging spacers. The introduction of a pyridine ring in Bppy-PTZ establishes intramolecular hydrogen bonding, stabilizing the quasi-axial (QA) conformation in the amorphous state, thereby facilitating multi-color and white-light emissions in thin-film and OLED devices. Photophysical and theoretical analyses reveal distinct emission behaviors from QA and quasi-equatorial conformations, with Bppy-PTZ exhibiting enhanced dual-emission and mechanochromic properties. Importantly, by adopting single-component Bppy-PTZ, the fabricated OLEDs realize color-tunable emissions, including blue, yellow, and adjustable white lights, reaching maximum external quantum efficiencies of up to 15.5%. This work provides valuable insights for the development of efficient single-component emitters affording multi-color OLEDs with high performances.

Keywords

conformational regulation / multi-color / organic light-emitting diode / single component / white emission

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2025 The Author(s). Aggregate published by SCUT, AIEI, and John Wiley & Sons Australia, Ltd.