High-Performance Fully Solution-Processed Oxide Thin-Film Transistors via Photo-Assisted Role Tuning of InZnO

The realization of next-generation flexible electronics involves the successful integration of functional solution-processed materials using simple and low-temperature fabrication techniques that are applicable to heat-sensitive substrates. Although there are numerous studies on the single solution-processed layer in an oxide thin-film transistor (TFT) structure, integrating all solution-based layers remains challenging. Here, fully solution-processed amorphous InZnO (a-IZO) TFTs were demonstrated utilizing the solution-based channel, gate insulator, and electrodes with a maximum fabrication temperature of 300 °C. Particularly, a single layer of a-IZO was used as both the channel and the source/drain electrode layer by selectively tuning the role of a-IZO as a semiconductor or a conductor through photo-assisted treatments. By employing a self-aligned TFT structure, the a-IZO electrodes were functionalized by UV irradiation and excimer laser annealing (ELA). The fully solution-processed a-IZO TFTs exhibited high performance with an average mobility of up to 38 cm2 V-1 s-1, which surpasses those of previously reported approaches for fully solution-processed oxide TFTs. Moreover, the overall device performance, including a subthreshold swing of 225 mV dec-1 and an on-voltage of -0.4 V, is comparable to those of vacuum-processed oxide TFTs. In-depth analyses suggest that the successful functionalization of the a-IZO semiconductor into conductive electrodes is due to oxygen vacancy generation after UV treatment and subsequent crystallization and densification of the irradiated a-IZO areas after ELA. The demonstration of simple low-temperature photofunctionalization of solution-based oxide materials can be applied to 3D printing and can advance the high-throughput display manufacturing such as roll-to-roll processing.