Stable Luminescent Radicals with Efficient Through-Space Charge-Transfer Emission

High-performance luminescent radicals featuring donor-radical (D-R) charge-transfer (CT) excited states have emerged as promising candidates for optoelectronic applications. However, prior studies have predominantly focused on through-bond charge-transfer (TBCT) mechanisms. In this work, we report the first examples of luminescent radicals based on TTM (tris(2,4,6-trichlorophenyl)methyl radical) with through-space charge-transfer (TSCT) excited states, represented by TPA-FR-TTM and CZP-FR-TTM. Spatial separation and non-bonding character between the donor and radical units minimizes electron-vibrational coupling and effectively suppresses non-radiative decay. As a result, CZP-FR-TTM exhibits an outstanding photoluminescence quantum efficiency (PLQE) of 64.3% and an ultralow non-radiative decay rate of 1.3 × 10⁶ s^-1, among the lowest ever reported for luminescent radicals. Furthermore, the reduced electronic coupling leads to non-Aufbau electronic structures, enhancing radical stability. These findings establish TSCT as a powerful design strategy for high-performance and stable luminescent radicals, opening new avenues for open-shell optoelectronic materials.