Enhancement on the performance of eco-friendly solution-processed InO/AlO thin-film transistors via lithium incorporation

Solution-processed fabrication of thin-film transistors (TFTs) has low cost and roll-to-roll capability. Indium oxide is one of the promising materials for the metal oxide semiconductor layer in TFTs. Early works used high temperature (∼700 °C) anneal, which is not suitable for flexible substrates. The toxic solvents, such as 2-methoxyethanol (2-Me), have been widely used in the preparation of precursor solutions. To overcome these challenges, we propose a low temperature (≤250 °C) and an eco-friendly process through the incorporation of lithium. Both X-ray photoelectron spectroscopy and electrical characterizations were carried out to optimize the process. The best result was obtained with 10 at.% lithium incorporation. The high field-effect mobility, averaged over 30 devices, is 21.6 cm² V⁻¹ s⁻¹, which is 380% higher than the groups without lithium incorporation and is higher than or comparable with those reported by early works for the low-temperature solution prepared InO films. They were used to build an inverter successfully. Moreover, the bias stability of the transistors was also proved to be improved through lithium doping. This eco-friendly solution process has the potential for low-cost fabrication of TFTs on the flexible substrate.