Near‐Infrared Electroluminescent Light‐Emitting Transistors Based on CVD‐Synthesized Ambipolar ReSe₂ Nanosheets

Abstract Near‐infrared light‐emitting technology is ideal for noncontact diagnostic medical imaging and high‐speed data communications. High‐quality ReSe₂ nanosheets of anisotropic single‐crystal structure with a bandgap of 1.26 eV (≈984 nm) are synthesized with an atmospheric pressure chemical vapor deposition (APCVD) method. The as‐synthesized ReSe₂ nanosheets‐fabricated light‐emitting transistors (LETs) exhibit nearly symmetric ambipolar characteristics in electrical transport. Judicious selection of asymmetric platinum (Pt)/chromium (Cr) electrodes, with their work functions matching respectively the conduction‐ and valence‐band edges of ambipolar ReSe₂, generates a low turn‐on voltage ReSe₂‐LET with the balanced number density and field‐effect mobility of bipolar carriers (i.e., electrons and holes). Room‐temperature near‐infrared electroluminescence (NIR EL) from the frequency‐modulated ReSe₂‐LET has been observed unprecedentedly with the assistance of a lock‐in detection system. The NIR EL intensity is tested by varying the bias voltage applied to the ReSe₂‐LET devices with different channel lengths. The wavelength of the NIR EL from ReSe₂‐LET is differentiated with optical bandpass filters. Room‐temperature angle‐dependent two lobe‐shaped EL pattern manifests the inherent anisotropic in‐plane excitonic polarization of the ReSe₂ crystal. The highly stable NIR EL from ReSe₂‐LETs provides prospective 2D material‐based ultrathin scalable data communication electronics for future development.