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.