The wavelength dependences of the optical transmittance spectra of the AZO films subjected to the threedifferentsubstratetemperaturesareplottedinFig.6.AlloftheAZOfilmsshowanaveragetransmittance of 82.3–88.8% in the visible wavelength range from 400 to 800 nm and a sharp fundamental absorption edge in the UV region, which is suitable for display devices and solar cells as transparent electrodes [28]. It seemed that the transmittance decreased and a red shift of the absorption edge occurred with increasing the substrate temperature. The transmittance may be reduced by increasing the surface bonding, which absorbs visible photons [29]. The absorption edge is related to the optical band gap, whichcan be calculated from the relationship between the optical absorption coefficient(a) and the transmittance (T). The optical band gap of a direct bandgap semiconductor canbe determined by using Tauc model [30]: