Transparent conductors as solar energy materials: A panoramic review

Present status of transparent conducting oxide thin-film development for Indium-Tin-Oxide (ITO) substitutes

High mobility, n-type transparent thin-film transistors (TTFTs) with a zinc indium oxide (ZIO) channel layer are reported. Such devices are highly transparent with ∼85% optical transmission in the visible portion of the electromagnetic spectrum. ZIO TTFTs annealed at 600 °C operate in depletion-mode with threshold voltages −20 to −10V and turn-on voltages ∼3V less than the threshold voltage. These devices have excellent drain current saturation, peak incremental channel mobilities of 45–55cm2V−1s−1, drain current on-to-off ratios of ∼106, and inverse subthreshold slopes of ∼0.8V∕decade. In contrast, ZIO TTFTs annealed at 300 °C typically operate in enhancement-mode with threshold voltages of 0–10V and turn-on voltages 1–2V less than the threshold voltage. These 300 °C devices exhibit excellent drain–current saturation, peak incremental channel mobilities of 10–30cm2V−1s−1, drain current on-to-off ratios of ∼106, and inverse subthreshold slopes of ∼0.3V∕decade. ZIO TTFTs with the channel layer deposited ne...

Transparent thin-film transistors with zinc indium oxide channel layer

Low resistivity transparent conducting Al-doped ZnO films prepared by pulsed laser deposition

The past two decades of vigorous interdisciplinary approaches has seen tremendous breakthroughs in both scientific and technological developments of bulk-heterojunction organic solar cells (OSCs) based on nanocomposites of π-conjugated organic semiconductors. Because of their unique functionalities, the OSC field is expected to enable innovative photovoltaic applications that can be difficult to achieve using traditional inorganic solar cells: OSCs are printable, portable, wearable, disposable, biocompatible, and attachable to curved surfaces. The ultimate objective of this field is to develop cost-effective, stable, and high-performance photovoltaic modules fabricated on large-area flexible plastic substrates via high-volume/throughput roll-to-roll printing processing and thus achieve the practical implementation of OSCs. Recently, intensive research efforts into the development of organic materials, processing techniques, interface engineering, and device architectures have led to a remarkable improvement in power conversion efficiencies, exceeding 11%, which has finally brought OSCs close to commercialization. Current research interests are expanding from academic to industrial viewpoints to improve device stability and compatibility with large-scale printing processes, which must be addressed to realize viable applications. Here, both academic and industrial issues are reviewed by highlighting historically monumental research results and recent state-of-the-art progress in OSCs. Moreover, perspectives on five core technologies that affect the realization of the practical use of OSCs are presented, including device efficiency, device stability, flexible and transparent electrodes, module designs, and printing techniques.

Bulk-Heterojunction Organic Solar Cells: Five Core Technologies for Their Commercialization.

Comparative study on structure and internal stress in tin-doped indium oxide and indium-zinc oxide films deposited by r.f. magnetron sputtering

Electrical and optical properties of gallium-doped zinc oxide films deposited by dc magnetron sputtering

Plasma emission control of reactive sputtering process in mid-frequency mode with dual cathodes to deposit photocatalytic TiO2 films

Aluminum-doped zinc oxide (AZO) films were deposited on glass substrates at 300°C by reactive mid-frequency (mf, 50 kHz) magnetron sputtering using dual magnetron cathodes with aluminum–zinc alloy targets. In order to keep the very high deposition rate stable in the transition region of the reactive sputtering system, the reactive gas (O2) flow was controlled using the "discharge impedance feedback system", where the discharge current value was used to control the O2 flow. The highest deposition rate for the transparent conductive AZO films achieved by this dual magnetron sputtering (DMS) system was 242 nm/min, which was higher by one order of magnitude than that achieved by the conventional reactive sputtering system. The lowest resistivity of the AZO film obtained by such a high deposition rate was 4.4×10-4 Ωcm. The structure and electrical properties of the films varied systematically by controlling the discharge current in the transition region using this system.

https://iopscience.iop.org/article/10.1143/JJAP.42.263/pdf

Impedance Control of Reactive Sputtering Process in Mid-Frequency Mode with Dual Cathodes to Deposit Al-Doped ZnO Films

Aluminum-doped zinc oxide (AZO) films were deposited on heated (300°C) glass substrates by reactive mid-frequency (mf, 50 kHz) magnetron sputtering using dual magnetron cathodes with aluminum–zinc alloy targets. In order to keep the very high deposition rate, reactive gas control using plasma emission was carried out to stabilize the discharge in the "transition region" of the reactive sputtering system. The highest deposition rate for the transparent conductive AZO films by this dual magnetron sputtering (DMS) system was 290 nm/min, which was higher than that for the conventional reactive sputtering system by one order of magnitude. The lowest resistivity of the AZO film was 3.9×10-4 Ω cm. The structure and electrical properties of the films could be controlled systematically by the reactive gas control system in the transition region.

Masato Kon

Papers

Comparative study on structure and internal stress in tin-doped indium oxide and indium-zinc oxide films deposited by r.f. magnetron sputtering

Electrical and optical properties of gallium-doped zinc oxide films deposited by dc magnetron sputtering

Plasma emission control of reactive sputtering process in mid-frequency mode with dual cathodes to deposit photocatalytic TiO2 films

Impedance Control of Reactive Sputtering Process in Mid-Frequency Mode with Dual Cathodes to Deposit Al-Doped ZnO Films

Al-Doped ZnO Films Deposited by Reactive Magnetron Sputtering in Mid-Frequency Mode with Dual Cathodes