Lightwave irradiation-assisted low-temperature solution synthesis of indium-tin-oxide transparent conductive films

Abstract

Transparent conductive oxide (TCO) films have important applications in many areas. Unfortunately, TCOs are usually fabricated using vacuum and high-temperature methods, preventing them from applications in low-cost flexible devices. In this paper, facile low-temperature sol-gel method is described that can be used to fabricate high-quality TCO films. This study uses lightwave (LW) irradiation (at ∼280 °C) with indium-tin-oxide (ITO) as a typical example. Both structure and key properties of ITO films are investigated for different LW irradiation conditions. ITO can be formed via LW irradiation after a period as short as 5 min. Furthermore, it is found that LW irradiation can promote the formation of M − O framework, effectively remove Cl impurities, and facilitate the elimination of hydroxyl oxygen defects - even at temperatures as low as ∼280 °C. The optimal ITO films show excellent electronic properties, including low sheet-resistance (14.5 Ω·sq−1) and high conductivity (1.7 × 103 S cm−1). Moreover, ITO films also show high transmittance (above 87%). Overall, our ITO films have a figure of merit (FOM) of 1.72 × 10−2 Ω−1, which is comparable to (or higher than) those of previous ITO films that were produced using conventional vacuum and high-temperature methods. Our LW irradiation method provides facile and effective approach to produce high-performance TCO films at remarkably low cost. This means these films could be used in affordable flexible large-area devices.