Amplifying Polarimetric Photoresponse through Oriented Colloidal Quantum Wells and Interfacial Band Engineering in ReSe2 Heterostructures

Abstract

Polarization-sensitive two-dimensional (2D) photodetectors are important for imaging, optical communication, and weak-signal recognition, yet their performance is often limited by the intrinsic anisotropy of the 2D semiconductor channel alone. Inspired by squid’s polarization-sensitive vision from ordered photonic platelets, where crystal orientation governs light’s polarization and appearance, we report a polarimetric photodetector by integrating face-down-oriented CdSe/ZnS colloidal quantum wells (CQWs) with 2D anisotropic ReSe2, followed by sulfur-ligand exchange to further optimize the interfacial energetics. The face-down assembly preserves the in-plane transition dipoles of CQWs at the film level, thereby enhancing polarization-selective light absorption, while sulfur-ligand exchange modifies the CQW band-edge positions and facilitates interfacial carrier extraction. As a result, the optimized face-down CQWs-S/ReSe2 device exhibits a dichroic ratio of 1.443, a polarization ratio of 27.57, a maximum responsivity of 2.3 A/W, and a rise time/decay time of 1.03/3.12 ms, together with improved specific detectivity of 4.56 × 1010 Jones and operational stability under the photoconductive effect at 635 nm. Spatially resolved photocurrent mapping further shows that the distinctive polarization-dependent photocurrent extends across the entire heterostructure channel, which is ascribed to the efficient type-II band alignment with appropriated band offsets between CQWs-S and ReSe2. These results demonstrate that combining orientationally ordered CQW films with ligand-engineered interfaces provides an effective route toward high-performance polarization-sensitive photodetectors to be used in polarized imaging and encrypted communication.