Combustion-assisted low-temperature solution process for high-performance SnO₂ thin-film transistors

In this study, high-performance SnO₂ thin-film transistors (TFTs) were fabricated at temperatures below 300 °C using the combustion-assisted sol-gel method. The internal energy induced by the exothermic reaction of the fuel and the oxidizer in the combustion precursors facilitates precursor conversion even at low processing temperatures, leading to the development of crystalline SnO₂. Compared to the conventional solution process, it was confirmed that the precursor was converted to crystalline SnO₂ at below 300 °C through thermogravimetric analysis, differential scanning calorimetry, and grazing incidence X-ray diffraction. In addition, X-ray photoelectron spectroscopy spectra indicate the formation of complete metal-oxygen-metal networks with an increase in the oxygen corresponding to the lattice, as well as a decrease in hydroxyl groups. As a result, compared with the conventional SnO₂ TFTs, the field-effect mobility of combustion-assisted SnO₂ TFTs increased significantly from 0.014 ± 0.01 to 2.43 ± 0.22 cm²/Vs at 250 °C (by ∼ 170 times) and from 0.38 ± 0.15 to 6.53 ± 0.41 cm²/Vs at 300 °C (by ∼ 17 times). Therefore, the combustion-assisted solution process is expected not only to realize fully low-cost solution-processed electronics by fabricating high-quality SnO₂ at low temperatures, but also to be combined with plastic substrates to fabricate flexible electronics.