We investigated quenching effects in solution-processed In-Ga-Zn-O (IGZO). Improved conductivity and crystallinity degradation occurred in quenched IGZO thin-films because of oxygen vacancy generation in a nominal stoichiometric system via defect formation resulting from temperature variation. The optical bandgap was red-shifted in quenched IGZO thin-films due to fluctuations in ionized impurities, such as In4+, Ga3+, and Zn2+, leading to band tailing. Fourier-transform infrared spectra confirmed that quenching effect by liquid nitrogen treatment resulted only from rapid decrement of temperature because there is no generation of chemical bonds during the soaking. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3605310] All rights reserved.