Interlayer Coupling in Organic-Inorganic Heterostructures via Interfacial F···S Interactions for Near-Infrared Photodetection and Real-Time Motion Recognition.

Abstract

Interlayer coupling serves as a powerful strategy for manipulating the optoelectronic characteristics of van der Waals heterostructures. Although the combination of organic and inorganic semiconductors has enabled versatile optoelectronic applications, interlayer coupling in organic-inorganic heterostructures is still limited by inherent material discrepancies such as lattice matching and stacking order. Herein, we demonstrate an interlayer-coupled organic-inorganic heterojunction achieved by interfacial noncovalent F···S interactions, which is composed of molecular 5,5''-bis(2-fluorophenyl)-2,2':5',2''-terthiophene (oF-PTTTP) and 2D molybdenum disulfide (MoS₂). By leveraging the conformational flexibility afforded by the full C─C single bonds in its backbone, the oF-PTTTP molecules can self-adjust their conformations upon thermal activation. The fluorine atoms on the side chains of oF-PTTTP engage in noncovalent interactions with the sulfur atoms of MoS₂ at the heterointerface, inducing a pronounced interlayer coupling effect accompanied by lattice strain. This coupling enables near-infrared (NIR) photodetection in a spectral range inaccessible to each individual component, yielding a specific detectivity of 1.8 × 10¹⁴ Jones at 808 nm, which is one of the highest values reported for organic-inorganic heterostructures. Furthermore, the device exhibits gate-tunable positive and negative photoresponses at 808 nm, allowing real-time motion imaging in the NIR spectrum.