Regulating Charge Distribution to Achieve High-Performance n-Type Single-Component Organic Neuromorphic Phototransistors

Abstract

Organic optoelectronic devices are advancing toward miniaturization and integration, demanding high performance, low energy consumption, and simplified manufacturing. The development of single-component phototransistors is still in its early stages, particularly for high-performance n-type polymer semiconductors. Here, thieno[3,2-b]thiophene-3,6-dicarbonitrile (2CNTT) is developed and a cyano-mediated torsion-polarization synergy strategy is proposed to construct conjugated polymers via direct (hetero)arylation polycondensation. This structural modification promotes intramolecular decoupling and enhances intermolecular interactions, enabling intra-/interchain charge distribution to be regulated. N-type copolymers based on 2CNTT exhibited broad visible-light absorption range and small exciton binding energy, capable of stable exciton generation and stepwise dissociation. The PFIID2NTT-based single-component phototransistor showed stable unipolar electron mobility and strong photoresponse with light-current/dark-current ratio as high as 9.02 × 104, and a paired-pulse facilitation index over 236% under visible light. The devices also operate at an ultra-low energy consumption (13.23 aJ), mimicking neural synapse behavior and enabling long-term memory functionality. The strategy optimizes charge distribution and exciton utilization in n-type polymer semiconductors, presenting a new paradigm for developing multifunctional organic optoelectronics.