Advanced beyond-silicon electronic technology requires discoveries of both new channel materials and ultralow-resistance contacts 1,2 . Atomically thin two-dimensional (2D) semiconductors have great potential for realizing high-performance electronic devices 1,3 . However, because of metal-induced gap states (MIGS) 4-7 , energy barriers at the metalsemiconductor interface, which fundamentally lead to high contact resistances and poor current-delivery capabilities, have restrained the advancement of 2D semiconductor transistors to date 2,8,9 . Here, we report a novel ohmic contact technology between semimetallic bismuth and semiconducting monolayer transition metal dichalcogenides (TMDs) where MIGS is sufficiently suppressed and degenerate states in the TMD are spontaneously formed in contact with bismuth. Through this approach, we achieve zero Schottky barrier height, a record-low contact resistance (R C ) of 123 Ω μm, and a recordhigh on-state current density (I ON ) of 1135 µA µm -1 on monolayer MoS 2 . We also demonstrate that excellent ohmic contacts can be formed on various monolayer semiconductors, including MoS 2 , WS 2 , and WSe 2 . Our reported R C values are a significant improvement for 2D semiconductors, and approaching the quantum limit. This technology unveils the full potential of high-performance monolayer transistors that are on par with the state-of-the-art 3D semiconductors, enabling further device down-scaling and extending Moore's Law.The electrical contact resistance at a metal-semiconductor (M-S) interface has been an increasingly critical, yet unsolved issue for the semiconductor industry, hindering the ultimate

Blue electrophosphorescence in organic light‐emitting diodes (OLEDs) is enhanced by the use of 3,6‐bis(triphenylsilyl)carbazole (see figure). This carbazole derivative with sterically bulky and large‐gap triphenylsilyl groups is an electrochemically and morphologically stable efficient host material for blue electrophosphorescence. When utilized in OLEDs, high efficiencies of up to 16 %, 30.6 cd A–1, and 26.7 lm W–1 are achieved.

We in situ probed the surface band bending (SBB) by ultraviolet photoelectron spectroscopy (UPS) in conjunction with field-effect transistor measurements on the incompletely depleted ZnO nanowires (NWs). The diameter range of the NWs is ca. 150-350 nm. Several surface treatments (i.e., heat treatments and Au nanoparticle (NP) decoration) were conducted to assess the impact of the oxygen adsorbates on the SBB. A 100 °C heat treatment leads to the decrease of the SBB to 0.74 ± 0.15 eV with 29.9 ± 3.0 nm width, which is attributed to the removal of most adsorbed oxygen molecules from the ZnO NW surfaces. The SBB of the oxygen-adsorbed ZnO NWs is measured to be 1.53 ± 0.15 eV with 43.2 ± 2.0 nm width. The attachment of Au NPs to the NW surface causes unusually high SBB (2.34 ± 0.15 eV with the wide width of 53.3 ± 1.6 nm) by creating open-circuit nano-Schottky junctions and catalytically enhancing the formation of the charge O(2) adsorbates. These surface-related phenomena should be generic to all metal oxide nanostructures. Our study is greatly beneficial for the NW-based device design of sensor and optoelectronic applications via surface engineering.

In this letter, we investigate electronic structures and electron-injection mechanisms of the effective cathode structures for organic light-emitting devices incorporating cesium carbonate ͑Cs 2 CO 3 ͒, either deposited as an individual thin injection layer or doped into the organic electron-transport layers. The electronic structures and the interface chemistry studied by ultraviolet and x-ray photoemission spectroscopy show that the enhanced electron injection is associated with strong n-doping effects and increase of electron concentrations in the electron-transport layer induced by Cs 2 CO 3. Since such a reaction occurs without the presence of metals, cathode structures incorporating Cs 2 CO 3 may be applied to a wide range of electrode materials.

We demonstrate the fabrication of solution-processed MoOx-treated (s-MoOx) silver nanowire (AgNW) transparent conductive electrodes (TCEs) utilizing low-temperature (sub-100 °C) processes. The s-MoOx aggregates around the AgNW and forms gauze-like MoOx thin films between the mesh, which can effectively lower the sheet resistance by more than two orders of magnitude. Notably, these s-MoOx-treated AgNW TCEs exhibit a combination of several promising characteristics, such as a high and broad transmittance across a wavelength range of 400 to 1000 nm, transmission of up to 96.8%, a low sheet resistance of 29.8 ohm sq(-1), a low haze value of 0.90%, better mechanical properties against bending and adhesion tests, and preferable gap states for efficient hole injection in optoelectronic applications. By utilizing these s-MoOx-treated AgNW TCEs as the anode in ITO-free organic light emitting diodes, promising performance of 29.2 lm W(-1) and 10.3% external quantum efficiency are demonstrated. The versatile, multi-functional s-MoOx treatment presented here paves the way for the use of low-temperature, solution-processed MoOx as both a nanowire linker and a hole injection interfacial layer for future flexible optoelectronic devices.