Solution-processed lithium-doped zinc oxide thin-film transistors at low temperatures between 100 and 300 °C

Lithium-doped zinc oxide (Li-ZnO) thin-film transistors (TFTs) were fabricated by solution process at the low temperatures ranged from 100 to 300 °C. Li-ZnO TFTs fabricated at 300 °C under nitrogen condition showed a mobility of 1.2 cm 2 /Vs. Most importantly, the mobility of Li-ZnO TFT devices fabricated at 100 °C could be increased significantly from 0.08 to 0.4 cm 2 /Vs by using double spin-coated and UV irradiation-treated Li-ZnO film, and the on-/off-current ratio is in the order of 10 6 . Notably, the XPS analyses proved that the performance improvement was originated from the chemical composition or stoichiometry evolution, in which the hydroxide was converted into metal oxide and accelerated the formation of the oxygen vacancies. Furthermore, low-voltage operating Li-ZnO TFTs were demonstrated by using a high-capacitance ion gel gate dielectrics. The Li-ZnO TFTs with an operating voltage as low as 2 V exhibited the carrier mobilities of 2.1 and 0.65 cm 2 /Vs for the devices treated at 300 and 100 °C, respectively. The low-temperature, solution-processed Li-ZnO TFTs showed greatly potential applications in flexible displays, smart label, and sensors.