Polarization‐Sensitive Photodetectors Based on Biaxially Grown Two‐Dimensional Organic Charge‐Transfer Cocrystals

ABSTRACT Organic polarization‐sensitive photodetectors are promising for simultaneously acquiring light intensity and polarization information, but their development is hindered by the one‐dimensional packing of conventional charge‐transfer (CT) cocrystals, which limits device integration and anisotropic optoelectronic modulation. Herein, two‐dimensional DTP‐TCNQ CT cocrystal microplates are fabricated by solution self‐assembly using dithieno[3,2‐b:2′,3′‐d]thiophene (DTP) as the donor and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) as the acceptor. Benefiting from strong intermolecular charge‐transfer interactions and an anisotropic crystal structure, the cocrystals exhibit broadband optical absorption and pronounced intrinsic optical anisotropy. DTP‐TCNQ‐based photodetectors achieve a specific detectivity of 2.29 × 10 14 Jones under 532 nm illumination, closely matching the noise‐derived value at 1 kHz. Moreover, devices constructed along the [100] and [011] directions show stable polarization‐dependent photoresponses, with polarization ratios of 7.40 and 6.61, respectively. Furthermore, time‐dependent density functional theory (TD‐DFT) calculations indicate that the orientation‐dependent response is associated with the alignment of the optical transition dipole moment, which forms angles of 17.8° and 78.5° with the [100] and [011] directions, respectively. This work offers guidance for designing anisotropic CT cocrystals and high‐performance organic polarization‐sensitive photodetectors with improved integration and functional modulation.