Electronic Structure, Transport, and Thermal Stability in Ternary Organic Shortwave Infrared Phototransistors

Abstract Short‐wave infrared (SWIR) organic photodetectors (OPDs) are promising alternatives to their inorganic counterparts due to their flexibility, low cost, and spectral tunability. However, strong photothermal effects and high integration density in electronics lead to considerable heat generation and device degradation. This study presents high‐performance SWIR phototransistors based on a ternary organic comprising PDVT‐10 and TMBP‐F2TCNQ cocrystal (TF2P). The devices achieve a responsivity of 548 A W ⁻¹ and detectivity of 6.8 × 10 ¹² Jones at 1060 nm, with a broad spectral response (1000–1800 nm) and high hole mobility (1.89 cm ² V ⁻¹ s ⁻¹ ). A key innovation is the bidirectional doping mechanism, where reciprocal charge transfer enhances carrier density and transport through optimized π–π stacking and interface dipoles. Ultrafast spectroscopy confirms a hole transfer time of 350 fs and more than fourfold mobility improvement compared to PDVT‐10 alone. Notably, the device maintains performance over 25–100 °C, with only a 25% drop in responsivity at 70 °C, demonstrating superior thermal stability. While mobility increases with temperature due to thermal activation, photoresponse declines, indicating that the cocrystal is sensitive to heat‐induced structural disorder. Significantly, this work offers a viable pathway for developing flexible, high‐sensitivity, and thermally stable SWIR OPDs for industrial use.