Molecularly thin organic single-crystalline p–n heterojunctions by interfacial heteroepitaxy for high-performance polarization-sensitive photodetectors

Abstract

Polarization-sensitive photodetectors (PSPs) are pivotal for navigation, security surveillance, and information encryption applications. While molecularly thin single-crystalline p–n heterojunctions with well-defined orientations represent an ideal material system for such applications, their fabrication remains challenging, and their polarization photodetection properties have not been thoroughly investigated. Here, we present an interfacial heteroepitaxy strategy to fabricate molecularly thin, single-crystalline p–n heterojunctions with precise orientation control and systematically explore their polarization-sensitive photodetection capabilities. Compared to conventional manually stacked p–n junctions, the interfacial heteroepitaxy-based devices demonstrate exceptional optoelectronic performance, achieving a photosensitivity (P) of 7.98 × 10⁴, a responsivity (R) of 942 A W⁻¹, and a specific detectivity (D*) of 1.08 × 10¹⁴ Jones. These metrics represent improvements of four orders of magnitude in P, a fourfold increase in R, and two orders of magnitude in D*. Furthermore, the optical anisotropy of the p–n heterojunctions yields a polarization ratio (PR) of 2.4. These results highlight the potential of molecularly thin p–n heterojunctions for high-performance PSPs.