Investigation of solution combustion-processed nickel oxide p-channel thin film transistors

In this work, p-channel thin film transistors (TFTs) with a nickel oxide (NiO) active layer have been synthesized by a solution combustion process. The effect of synthesis parameters was investigated. It was revealed that the metal–acetylacetone complexes and metal–ammine complexes coexist in the solution precursor. The combustion of metal–acetylacetone complexes is dominant in the redox reaction, while the combustion of metal–ammine complexes completes the reaction of residual organic matter. The proportion of both complexes in the solution precursor is key for NiO synthesis, which is tunable by the precursor aging time. The annealing temperature is another key parameter. X-ray photoelectron spectroscopy analysis indicates that organic residues exist in the film annealed at low temperature. In contrast, with the increase in annealing temperature, the Ni3+-related components decreased while the intensity of Ni2+ in the film increased. This results in a decrease in the hole concentration and the degradation of device performance. The p-channel NiO TFTs with a field-effect mobility of 0.015 cm2 V–1 s–1 have been achieved via systemically optimizing precursor aging time and post-annealing temperature. This study successfully demonstrates the potential of combustion solution-processed NiO TFTs with p-channel characteristics.