Printable Single-Unit-Cell-Thick Transparent Zinc-Doped Indium Oxides with Efficient Electron Transport Properties

Abstract

Ultrathin transparent conductive oxides (TCOs) are emerging candidates for next-generation transparent electronics. Indium oxide (In2O3) incorporated with post-transition-metal ions (e.g., Sn) has been widely studied due to their excellent optical transparency and electrical conductivity. However, their electron transport properties are deteriorated at the ultrathin two-dimensional (2D) morphology compared to that of intrinsic In2O3. Here, we explore the domain of transition-metal dopants in ultrathin In2O3 with the thicknesses down to the single-unit-cell limit, which is realized in a large area using a low-temperature liquid metal printing technique. Zn dopant is selected as a representative to incorporate into the In2O3 rhombohedral crystal framework, which results in the gradual transition of the host to quasimetallic. While the optical transmittance is maintained above 98%, an electron field-effect mobility of up to 87 cm2 V–1 s–1 and a considerable sub-kΩ–1 cm–1 ranged electrical conductivity are achieved when the Zn doping level is optimized, which are in a combination significantly improved compared to those of reported ultrathin TCOs. This work presents various opportunities for developing high-performance flexible transparent electronics based on emerging ultrathin TCO candidates.

Recent advances in the fabrication of 2D metal oxides

“…Recently, Jannat et al. selected Zn as a dopant to prepare doped liquid metals with different concentrations (between 0 and 5 atomic %), achieving large-area 2D indium zinc oxide (IZO) by utilizing the same squeeze-printing method mentioned above ( Jannat et al., 2021 ). The optimum electron mobility is realized in the sample with lower Zn dopant concentrations, presenting an almost 20 times improvement compared to that of pure 2D In 2 O 3 .…”

Liquid metals: an ideal platform for the synthesis of two-dimensional materials

“…13a-c). 117 These studies highlight that liquid metal derived nanosheets possess electronic properties that are defined by the fundamental nature of the synthesised material. While being comparatively simple, the printing methods can produce excellent semiconductors that may find application in practical devices.…”

Recent Progress on Asymmetric Carbon- and Silica-Based Nanomaterials: From Synthetic Strategies to Their Applications

“…Some new synthetic techniques can also be used to prepare some emerging asymmetric materials [126][127][128]. For instance, zinc-doped indium oxide has been successfully printed on the silica surface to obtain asymmetric 2D silica nanocomposite [129].…”