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Unveiling the TADF Emitters with Apparent Negative Singlet‐Triplet Gaps: Implications for Exciton Harvesting and OLED Performance by Xinrui Chen; Sergey Bagnich; Robert Pollice; Bing Li; Yuanyuan Zhu; Rishabh Saxena; Yixiao Yin; Weiguo Zhu; Alan Aspuru‐Guzik; Eli Zysman‐Colman; Anna Köhler; Yafei Wang is a Engineering article available to read on EtoBox.

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## Abstract Intramolecular through‐space charge transfer thermally activated delayed fluorescence (TSCT‐TADF) has attracted much attention recently as it can achieve both small energy splitting and high emission efficiency. However, the relationship of excited states between TSCT and through‐bond charge transfer (TBCT) remains a challenge in the TSCT‐TADF molecules. Herein, three compounds DPS‐__m__‐bAc, DPS‐__p__‐bAc, and DPS‐OAc that possess emissive TSCT and/or TBCT states are prepared. Interestingly, a so‐called inverted energy gap is found for both DPS‐__m__‐bAc and DPS‐__p__‐bAc in toluene solution, which results from the different charge transfer states of ICT~high~ and ICT~low~, as proved by the detailed transient photoluminescence and calculated results. Intense emission from blue to yellow associated with high photoluminescence quantum yields of 70–100% are measured in doped polymethyl(methacrylate) (PMMA) films. Notably, compound DPS‐__m__‐bAc achieves the highest reverse intersystem crossing rate constant (__k__~RISC~) of over 10^7^ s^−1^ in a PMMA film, benefiting from close‐lying TSCT and TBCT states. The solution‐processed device with DPS‐__m__‐bAc displays a maximum

Who reads Unveiling the TADF Emitters with Apparent Negative Singlet‐Triplet Gaps: Implications for Exciton Harvesting and OLED Performance?

Author

Xinrui Chen; Sergey Bagnich; Robert Pollice; Bing Li; Yuanyuan Zhu; Rishabh Saxena; Yixiao Yin; Weiguo Zhu; Alan Aspuru‐Guzik; Eli Zysman‐Colman; Anna Köhler; Yafei Wang

Publisher

Wiley

Published

2023

Field

Engineering (Physical Sciences)