In-depth studies on rapid photochemical activation of various sol-gel metal oxide films for flexible transparent electronics

Despite intensive research on photochemical activation of sol-gel metal oxide materials, the relatively long processing time and lack of deep understanding of the underlying chemical courses have limited their broader impact on diverse materials and applications such as thin-film electronics, photovoltaics, and catalysts. Here, in-depth studies on the rapid photochemical activation of diverse sol-gel oxide films using various spectroscopic and electrical investigations for the underlying physicochemical mechanism are reported. Based on the exhaustive chemical and physical analysis, it is noted that deep ultraviolet-promoted rapid film formation such as densification, polycondensation, and impurity decomposition is possible within 5 min via in situ radical-mediated reactions. Finally, the rapid fabrication of all-solution metal oxide thin-film-transistor circuitry, which exhibits stable and reliable electrical performance with a mobility of >12 cm² V^-1 s^-1 and an oscillation frequency of >650 kHz in 7-stage ring oscillator even after bending at a radius of <1 mm is demonstrated. The general physicochemical mechanisms underlying photoactivated sol-gel reactions are described, with comprehensive chemical and structural analysis inducing rapid (<5 min) fabrication of various metal oxide films at low temperatures (<150 C), and all-solution processed high-performance electronic devices and circuitry on ultrathin polymeric substrates are demonstrated. This will open new possibilities to prepare future electronic materials in a fast, scalable, and economic manner.