Coupling between Pyroelectricity and Built-In Electric Field Enabled Highly Sensitive Infrared Phototransistor Based on InSe/WSe2/P(VDF-TrFE) Heterostructure

Ferroelectricity-Driven Self-Powered Weak Temperature and Broadband Light Detection in MoS2/CuInP2S6/WSe2 van der Waals Heterojunction Nanoarchitectonics

Two-dimensional ferroelectric materials enrich the modulation degrees of freedom in self-powered van der Waals temperature/light detectors by incorporating pyroelectric and bulk photovoltaic effects. However, in addition to the low polarization, the practical applications of these materials are limited due to the significant challenge posed by their ultrathin nature, which affects their polarization stability. In this report, we introduce a design for a dual heterostructure-stabilized van der Waals heterojunction that addresses this challenge by improving the performance and extending the operational lifetime of self-powered van der Waals temperature/light detectors. The design is demonstrated using the MoS2/CuInP2S6 (CIPS)/WSe2 van der Waals heterojunction, which exhibits sensitivity to small temperature changes induced by weak light across the ultraviolet to mid-infrared spectrum. It can generate a noticeable pyroelectric current without the need for an external voltage, and its pyroelectric coefficient exceeds 130 and 978 μC/m2 K for 45 and 70 nm CIPS, respectively. The heterojunction offers high detection accuracy, with a temperature variation sensitivity as small as 0.1 K and an optical power intensity detection range from low to 1 μW/cm2. Additionally, the heterojunction exhibits exceptional detectivity (D*) for different light wavelengths. Remarkably, the self-powered detection performance remains stable for months without obvious degradation in the natural environment. These results offer a promising solution for high-performance, self-sustaining temperature/light detection applications and pave the way for the development of future ferroelectricity-driven photodetection technologies.

Controlling Electron/Hole Recombination in Near-Infrared Polymer Phototransistors through an Insulation Medium: A Pathway to Ultrahigh Photosensitivity

In near-infrared (NIR) polymer phototransistors, the photoresponse is proportional to the turn-on voltage shift (ΔVth). Due to the narrow band gap of NIR polymers, the ΔVth value is usually small. However, the use of a single bulk heterojunction (BHJ) layer has a minimal effect on increasing the value of ΔVth. This is because doping with high concentrations of acceptors results in strong current traps and accelerates electron/hole recombination. In this work, a new strategy is proposed to control the recombination of electrons/holes. By doping an insulating medium made of polystyrene (PS) into BHJs, PC61BM:PS:PDPP3T-based ternary NIR phototransistors with high acceptor concentrations were prepared by using a one-step film transfer method (FTM). Compared with a PC61BM:PDPP3T-based binary device (1:1), a ternary device (1:1:1) exhibited a significant performance improvement. The ΔVth value (∼29.5 ± 1.0 V) increased by approximately 4-fold, the Iph/Idark (∼4.4 × 106) increased by a factor of 3000 to 4000-fold, and the dark current decreased by 2-3 orders of magnitude (@ Vg = 0 V). Additionally, the ternary devices demonstrated excellent performance across a wide ternary ratio range (1:1:1 to 4:2:1).