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.

High-Performance Photodetector Based on the ReSe2/PtSe2 van der Waals Heterojunction

“…In the thin ReSe 2 region, the Raman signals caused by the in-plane vibration (E g ) is located at ≈118/123 cm –1 and the Raman signals at ≈158/172 cm –1 and ≈284/294 cm –1 are caused by the out-of-plane vibration (A g ) (Figure c, blue line). These results are consistent with the previous report for the ReSe 2 film . In the PtSe 2 region, the peak corresponding to the E g phonon mode and the A 1g mode were respectively observed at 175 cm –1 and 205 cm –1 (Figure c, red line), and the inconspicuous feature at ∼230 cm –1 is attributed to an overlap between the E u and A 2u modes, which are longitudinal optical (LO) modes of in-plane and out-of-plane motions of platinum and selenium atoms, respectively.…”

“…These results are consistent with the previous report for the ReSe 2 film. 52 In the PtSe 2 region, the peak corresponding to the E g phonon mode and the A 1g mode were respectively observed at 175 cm −1 and 205 cm −1 (Figure 1c, red line), and the inconspicuous feature at ∼230 cm −1 is attributed to an overlap between the E u and A 2u modes, which are longitudinal optical (LO) modes of in-plane and out-of-plane motions of platinum and selenium atoms, respectively. This is consistent with the previous report for PtSe 2 film.…”

Interfacial Properties of Anisotropic Monolayer SiAs Transistors

“…Most of the studied 2D semiconductors have isotropous characteristics in planes with highly symmetrical crystal structures. Two-dimensional semiconductors with asymmetrical crystal structures possess anisotropic electronic and optical properties, etc., which brings a new degree of freedom in the plane [11][12][13][14][15][16]. Therefore, various advanced equipment related to angles is designed based on the 2D anisotropic semiconductors, such as photoelectric detectors, anisotropic memory, and gas sensors [17][18][19].…”