Intermolecular Charge-Transfer-Induced Strong Optical Emission from Herringbone H-Aggregates

Superior organic light-emitting transistors (OLETs) materials require two conventionally exclusive properties: strong luminescence and high charge mobilities. We propose a three-state model through localized diabatization to quantitative analyze excited state structures for various herringbone (HB) H-aggregates and demonstrate that for some investigated systems, the low-lying intermolecular charge-transfer (CT) state couples with the bright Frenkel exciton (FE) and forms a dipole-allowed S₁ that lies below the dark state, proceeding strong luminescence. Specifically, such conversion in luminescence properties occurs when the electron- and hole-transfer integrals ( and ) are of the same sign and is notably larger than the excitonic coupling (J), i.e., . This theoretical finding can not only explain and rationalize recent experimental results on DPA and dNaAnt, both with OLET property, but also unravel an exciting scenario where strong luminescence and high charge mobilities are compatible, which will considerably broaden the aperture of novel OLET design.