Dopant-Tailored Matrices: A Crystal Engineering Strategy for Organic Room-Temperature Phosphorescent Host-Guest Systems and Beyond.

Host-guest doping of molecular crystals is a powerful strategy to tune optoelectronic properties, yet achieving precise host-dopant compatibility and beneficial synergy without introducing detrimental effects caused by dopant-induced disorders remains challenging. Here, a new crystal engineering strategy is introduced in which host matrices are rationally designed to accommodate a predefined class of dopants and promote favorable host-guest interactions. This tailored-dopant matrix concept is demonstrated for dopant-induced organic room-temperature phosphorescence (RTP) using carbazole-based matrices and benzoindole-based dopants, a prototypical RTP system. Guided by the hypothesis that a herringbone packing of carbazole units promotes synergistic structural interactions with the dopant, a multiscale theoretical methodology is first developed to elucidate the intermolecular interactions stabilizing this motif in pristine carbazole-based crystals. These insights enable the design and synthesis of new host architectures exhibiting the targeted packing arrangement. Ultimately, the resulting single-crystalline host-guest materials exhibit long-lived organic RTP, with phosphorescence lifetimes of several hundred milliseconds. This work could establish dopant-tailored crystal engineering as a potential new paradigm for designing functional doped organic semiconductor crystals with tailored optoelectronic properties.