Synthesis of Gallium-Doped Zinc Oxide (GZO) Nanoparticles for GZO/Silver Nanowire Nanocomposite Transparent Conductive Electrodes THI BICH HAO HUYNH, 1 DUC THANH CHU, 1 VAN HOAN HOANG, 1 THI THU HIEN NGUYEN, 1 THANH TUNG DUONG, 1,4 VAN ANH TRAN, 3 THANH HUY PHAM, 2 and DUY CUONG NGUYEN 1,5 1.—Nano Optoelectronics Laboratory, Advanced Institute for Science and Technology, Hanoi University of Science and Technology, No. 1 Dai Co Viet, Hai Ba Trung, Hanoi, Vietnam. 2.—Department of Materials Science and Engineering, Phenikaa University, Yen Nghia, Ha Dong, Hanoi, Vietnam. 3.—National Center for Technological Progress, Hanoi, Vietnam. 4.—e-mail: Tungduong1084@yahoo.com. 5.—e-mail: cuong.nguyenduy@hust.edu.vn Gallium (Ga)-doped zinc oxide nanoparticles (GZO-NPs) have been synthe- sized using a heating-up method. The Ga doping concentration strongly af- fected the particle size, distribution, and bandgap energy of the GZO-NPs. When the Ga concentration was increased from 0% to 5%, the average size of the GZO-NPs decreased from 57 nm to 16 nm while the bandgap increased from 3.14 eV to 3.26 eV. On further increase of the Ga content to 7% and 9%, the particle size increased while the bandgap narrowed. The GZO-NPs syn- thesized with 5% Ga showed the best uniformity and smallest average diameter of approximately 16 nm. The GZO-NPs with 5% Ga were applied to reduce the mechanical contact between the AgNWs in GZO/silver nanowire (AgNW) composite for application as a transparent conductive electrode, yielding R SH = 18.1 X/h, T = 77.8% at 550 nm, and r DC /r Op = 77.53. These results indicate that such GZO-NPs are a very promising nanocrystalline ink precursor for printing thin films for application in nanocomposite transparent conductive electrodes. Key words: Gallium-doped zinc oxide, nanoparticles, bandgap, heating-up method, inks for printing film, GZO NP/ AgNW nanocomposite INTRODUCTION In recent years, silver nanowires (AgNWs) have been considered to replace transparent conductive oxide (TCO) films in various applications, including as precursors for TCO thin-film fabrication, low-e glass (infrared reflection), displays, touchscreens, electronics, electromagnetic interference, and static protection. 1–4 Several groups have reported that electrodes using AgNW networks show high trans- mittance and low sheet resistance (R SH ), reaching values comparable to those of conventional indium (In)-doped tin oxide (ITO) films. However, the junction resistance between two AgNWs is very high due to their mechanical contact. 5 In previous work, we coated ZnO onto AgNWs using atomic layer deposition (ALD). The 200-cycle ZnO produced using ALD showed the best quality, with R SH of 11 X/h and transmittance of 75%; 6 however, the ALD method is expensive. Moreover, the undoped ZnO still showed low conductivity. Among TCO materials, ITO is still used, mainly because of its attractive properties such as low resistivity (q =1 9 10 4 X cm to 2 9 10 4 X cm) and high transmittance ( > 85%) in the visible region. 7 How- ever, ITO is expensive because it contains the rare- (Received March 5, 2020; accepted March 26, 2020; published online April 8, 2020) Journal of ELECTRONIC MATERIALS, Vol. 49, No. 6, 2020 https://doi.org/10.1007/s11664-020-08129-3 Ó 2020 The Minerals, Metals & Materials Society 3964