Thin film transistors (TFTs) are important electronic switching devices made by depositing thin films of an active semiconductor as well as the dielectric layer and metal electrode over a supporting substrate, which primarily used for large-area flat panel displays. TFT can be made using a wide variety of semiconductor materials from conventional amorphous silicon to recently organic and inorganic materials.
Metal oxide semiconductors are promising candidates for making transparent thin-film transistor circuitry, which has been extensively studied due to their favorable field-effect mobility, excellent environmental and thermal stability, high optical transparency, and high uniformity in large scale fabrication applications. Furthermore, the availability of solution-processed metal-oxide semiconductors open an avenue to fabricate metal oxide TFTs by direct printing processes. However, the majority of solution-processed metal oxide semiconductors are n-channel materials.
The availability of P-type semiconductor channel materials will enable Complementary Metal-Oxide-Semiconductor (CMOS) circuits which offer the benefits of lower power consumption, less heat generation, higher circuit density, higher noise-margin, and simpler architecture over circuits built on unipolar TFTs. Low temperature fabrication of printed p-type CuI TFTs was reported for the first time by our group . One layer of CuI thin film was fabricated by inkjet printing the Copper iodide precursor ink directly onto the device substrate followed by immediate crystallization of CuI nanoparticles as the solvent evaporated. The substrate temperature during inkjet printing was varied in order to obtain continuous CuI films with large grain size for improved device performance. In this presentation, we will report the fabrication and characterization of p-type thin film transistors on flexible substrates by the combination of inkjet printing and photonic sintering.
 Choi, Chang-Ho, Jenna Y. Gorecki, Zhen Fang, Marshall Allen, Shujie Li, Liang-Yu Lin, Chun-Cheng Cheng, and Chih-Hung Chang. "Low-temperature, inkjet printed p-type copper (I) iodide thin film transistors." Journal of Materials Chemistry C 4, no. 43 (2016): 10309-10314.
This work was supported by the US National Science Foundation [CMMI #1537196, CBET# 1449383] and the Walmart Manufacturing Innovation Foundation.