Isostructural Doping in Ultrathin Molecular Crystals for Temperature-Immune and Ultralow-Power Organic Electronics

Molecular doping is essential for enhancing the electrical performance of organic semiconductors in transistors and integrated circuits. However, in high-crystalline, ultrathin molecular semiconductors, conventional heteromolecular doping frequently induces disorder and disrupts molecular packing, leading to phase segregation, dopant diffusion, and impaired charge transport. Here, we report an isostructural doping strategy based on the monofluorinated derivative dopant 2-decyl-7-(4-fluorophenyl)[1]benzothieno[3,2-b][1]benzothiophene (F-Ph-BTBT-C₁₀) of the high-mobility asymmetric semiconductor 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C₁₀). This approach is designed to enhance charge transfer and boost the intrinsic hole density, especially in ultrathin films, while providing a means for promoting miscibility and preserving the crystalline order. We realize organic field-effect transistors with high electrical conductivities, low off-state current, bidirectional threshold voltage modulation, and an optimized contact. Furthermore, we demonstrate wide-temperature-range temperature-immune transistors with prolonged stability, and inverters exhibiting high gain (55 V V^-1) and ultralow static power consumption (900 pW). This isostructural doping strategy provides a generalizable pathway toward stable ultralow-power, high-performance organic electronic devices.