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

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.