A study of the characteristics of indium tin oxide after chlorine electro-chemical treatment. (October 2016)

• Record Type: Journal Article
• Authors: Kim, Moonsoo; Kim, Jongmin; Cho, Jaehee; Kim, Hyunwoo; Lee, Nayoung; Choi, Byoungdeog
• Is Part Of: Materials research bulletin. Volume 82(2016)
• Page Start: 115
• Page End: 121
• Publication Date: 2016-10
• Subjects: A. Metals (indium tin oxide) -- B. Chemical synthesis (chlorination) -- D. Electrical properties (electro-negativity) -- D. Surface properties (surface dipole) -- D. Fermi surface (vacuum level shift); Materials -- Periodicals; Crystal growth -- Periodicals; Matériaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Crystal growth; Materials; Periodicals; 620.11
• DOI: 10.1016/j.materresbull.2016.03.008
• Languages: English
• ISSNs: 0025-5408

Abstract

Graphical abstract: The presence of Chlorine in the outer surface resulted in a highly electro-negative surface states and an increase in the vacuum energy level. Highlights: We investigated the influence of chlorine surface treatment on ITO properties. Chlorination induced the change of the electro-static potential in the outer surface. Chlorine electro-chemical treatment of ITO is a simple, fast and effective technique. Abstract: In this work, we investigate the influence of a chlorine-based electro-chemical surface treatment on the characteristics of indium tin oxide (ITO) including the work function, chemical composition, and phase transition. The treated ITOs were characterized using X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS), 4-point probe measurements, and grazing incidence X-ray diffraction (GI-XRD). We confirmed a change of the chemical composition in the near-surface region of the ITO and the formation of indium-chlorine (In-Cl) bonds and surface dipoles (via XPS). In particular, the change of the electro-static potential in the outer surface was caused by chlorination. Due to the vacuum-level shift after the electro-chemical treatment in a dilute hydrochloric acid, the ITO work function was increased by ∼0.43 eV (via UPS); furthermore, the electro-negativity of the chlorine anions attracted electrons to emit them from the hole transport layer (HTL) to the ITO anodes, resulting in an increase of the hole-injection efficiency.