Graphene-Boosted PBTTT-C14/F4-TCNQ Donor/Acceptor Complexes for Room-Temperature Near-Infrared Photodetection and Imaging

Organic near-infrared (NIR) photodetectors have attracted considerable interest as candidates for flexible, lightweight, and low-cost optoelectronic technologies. However, achieving efficient NIR absorption and high photodetection sensitivity simultaneously remains a significant challenge for most organic semiconductor systems. Here, a high-performance hybrid organic phototransistor is developed by combining a PBTTT-C 14 /F4-TCNQ donor–acceptor charge-transfer complex with monolayer graphene. Strong intermolecular charge-transfer interactions generate low-energy electronic transitions, resulting in broadband optical absorption spanning 400–1300 nm. Meanwhile, the incorporation of graphene provides an efficient transport pathway for photogenerated carriers and promotes charge separation, thereby enhancing photoconductive gain. As a result, the hybrid device exhibits excellent NIR photodetection performance under 800 nm illumination, delivering a responsivity of 1.67 × 10 5 A/W, a detectivity of 3.26 × 10 12 Jones, and an external quantum efficiency of 2.92% × 10 7 %. Notably, a measurable photoresponse is maintained even under extremely weak irradiation, demonstrating outstanding sensitivity toward low-intensity optical signals. In addition, the device shows stable switching behavior with millisecond-scale response characteristics. Integration into a phototransistor array further enables spatially resolved NIR imaging. These results highlight the effectiveness of integrating charge-transfer complexes with two-dimensional conductive materials and provide a viable strategy for next-generation high-gain organic infrared sensing and imaging applications.