Ground-State Charge-Transfer Doping Interactions in Donor–Acceptor Semiconducting Polymers

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Conjugated polymers are at the heart of numerous current and emerging technologies. Doping, a process by which charge carriers are introduced, is crucial to their functionality and performance. Despite significant historical context and the exploration of a broad chemical space, doping processes that are activated by formation of a ground-state charge-transfer complex (GS-CTC), which is mediated by the supramolecular hybridization between the frontier molecular orbitals of distinct molecular species, remain poorly understood. There are no clear demonstrations of this phenomena in contemporary donor–acceptor (DA) conjugated polymers (CP). Here, using diketopyrrolopyrrole-based donor–acceptor semiconducting polymers and a -conjugated penta-t-butylpentacyanopentabenzo[25]annulene “cyanostar” macrocycle, we demonstrate the first examples of features that control GS-CTC formation in contemporary DA CP frameworks. Using complementary experimental techniques and theory, we articulate how subtle molecular, electronic, and solid-state features impact supramolecular hybridization of the frontier molecular orbitals and impact the resultant (opto)electronic, magnetic, and transport properties. These studies demonstrate that subtle effects arising from the admixture between distinct -conjugated materials can have dramatic outcomes on properties and performance through modification of the density of states (DOS). These results will enable completely new design rules for organic semiconductors with precise property control.