Programmable Organic Quasi-Superlattices with Molecular-Monolayer Precision for Enhanced Photoconductive Response.

Engineering van der Waals organic heterostructures with monolayer precision offers a powerful route to modulate charge transport and light-matter interactions in molecular systems. However, deterministic multilayer assembly remains challenging due to pervasive interlayer interdiffusion and the lack of generally applicable high-precision deposition strategies. Here, we introduce programmable organic quasi-superlattices enabled by the integration of air-water interfacial monolayer assembly with sequential transfer stacking, allowing polymeric semiconductors to be organized into periodic architectures with molecular-layer precision. By systematically tuning the number of periods, the intraperiod composition, and the thickness of the tunneling spacers, these quasi-superlattices exhibit markedly enhanced photoconductive performance, achieving signal-to-noise ratios of up to 2 × 106 under white-light illumination together with an ultralow dark current density on the order of 10-10-10-11 A cm-2. Superlattices optimized for near-infrared detection (900 nm) achieve a detectivity of 2.06 × 1012 Jones and a photoresponse time of less than 0.2 s under ultralow illumination (21 μW cm-2). These findings establish programmable molecular organization as a general strategy for accessing emergent optoelectronic functionality from vast chemical spaces via the controlled assembly of organic multilayer architectures.