Bright electroluminescence in ambient conditions from WSe2 p-n diodes using pulsed injection

Abstract

High-performance monolayer MoS 2 field-effect transistor with large-scale nitrogen-doped graphene electrodes for Ohmic contact Applied Physics Letters 115, 012104 (2019);

A High‐Efficiency Wavelength‐Tunable Monolayer LED with Hybrid Continuous‐Pulsed Injection

“…As the counterpart of the DC driving LED, the alternating current (AC) driving LED, also known as pulsed LED, has attracted more attention recently. [10,11] Compared with DC LED structure, the AC LED only uses the twoterminal capacitor structure via a single metal-semiconductor contact, which significantly simplifies the fabrication. The electron charging and discharging effect in this capacitor structure will lead to pulsed light emission.…”

Excitonic Emission in Atomically Thin Electroluminescent Devices

“…[1,92] However, via constructing interlayer direct bandgap at Γ point in multilayer TMDC/multilayer InSe heterobilayer architectures, [94] indirect bandgap TMDC films may also show high quantum efficiencies in luminescent applications. Furthermore, originated from spin-orbit coupling, large Transient LED WS 2 0.27% 300 −− Simple structure [53] Transient LED WSe 2 1% 300 −− p-n junction [52] Transient LED WSe 2 −− 4 −− Exciton complex [54] spin splittings (≈400 meV for tungsten-based TMDCs and ≈200 meV for molybdenum-based TMDCs, top panel in Figure 1a) are opened up in the valence band at K valleys, which give rise to the A (lower energy direct transition) and B (higher energy direct transition) excitons. [20,22,79,95,96] And a considerably smaller spin splitting ≈tens of meV [69] is formed in the conductance band at K valleys of TMDCs.…”

“…So far, multiple types of 2DLEDs, including vertical and lateral p–n junctions, [ 11,14,32,36–43 ] quantum well (QW) structures, [ 15,33,44,45 ] metal–semiconductor–insulator (MIS) structures, [ 46–51 ] and transient‐2DLEDs, [ 52–54 ] have been fabricated. Among these devices, emission wavelength, intensity, quantum efficiency, and luminescent area that are considered as key parameters for LEDs vary according to different structures, emission mechanisms, and active materials (luminescent materials).…”

“…[17,31] Furthermore, since interlayer interactions in layered materials are van der Waals force, different 2D layered materials, such as insulating hexagonal boron nitride (h-BN), semimetallic graphene and semiconducting TMDCs (H-phase) and BP can be arbitrarily stacked into heterostructures to form p-n junctions, [32] tunneling junctions [33] or type II heterobilayers [34] that are of fundamental importance for exploration of exciton related physics and electrically driven excitonic emission. [35] So far, multiple types of 2DLEDs, including vertical and lateral p-n junctions, [11,14,32,[36][37][38][39][40][41][42][43] quantum well (QW) structures, [15,33,44,45] metal-semiconductor-insulator (MIS) structures, [46][47][48][49][50][51] and transient-2DLEDs, [52][53][54] have been fabricated. Among these devices, emission wavelength, intensity, quantum efficiency, and luminescent area that are considered as key parameters for LEDs vary according to different structures, emission mechanisms, and active materials (luminescent materials).…”

Two-dimensional materials for light emitting applications: Achievement, challenge and future perspectives

“…For example, the PL can be tuned by substrate screening effect [39], temperature and even excitation power [40], while the EL can be adjusted by different geometry, current injection method, and electrostatic doping. Meanwhile, the PL and EL emission from those 2D materials provide a great platform for studying light-matter interaction including exciton dynamics, high order exciton behaviors, excitonic circuit and even exciton condensate [41][42][43][44][45][46]. Therefore, the light emitting applications in 2D materials system play a significant role in studying those ultra-thin semiconductors.…”