Excitation‐Dependent and Efficient Phosphorescence Based on Benzophenone Derivatives

Abstract The design of organic molecules with high photoluminescence quantum efficiency and adjustable emission colors has led to the development of high‐performance optoelectronic devices. However, the task of generating color‐tunable luminescence originating from different excited states has achieved limited success. Here, a design strategy is presented for improving phosphorescence quantum efficiency and extending emission spectral range by introducing high luminous acenes in benzophenone derivatives. The experimental data reveal that the maximum phosphorescence efficiency of the designed molecule can reach 84% in solution and 61% in crystals, which is the most efficient benzophenone phosphor so far. Importantly, the excited states can be selectively expressed by varying the excitation wavelengths, including thermally activated delayed fluorescence (TADF) from T 2 to S 1 excited state, and dual phosphorescence from T 2 and T 1 excited states. The design strategy of using rigid acenes to suppress nonradiative transition provides an opportunity to improve phosphorescence efficiency comparable with fluorescence efficiency, presenting great potential in high‐performance optoelectronic devices.