Inkjet‐Printed Ternary Oxide Dielectric and Doped Interface Layer for Metal‐Oxide Thin‐Film Transistors with Low Voltage Operation

Abstract

Additive solution process patterning, such as inkjet printing, is desirable for high‐throughput roll‐to‐roll and sheet fabrication environments of electronics manufacturing because it can help to reduce cost by conserving active materials and circumventing multistep processing. This paper reports inkjet printing of YxAl2−xO3 gate dielectric, In2O3 semiconductor, and a polyethyleneimine‐doped In2O3 interfacial charge injection layer to achieve a thin‐film transistor (TFT) mobility (μsat) of ≈1 cm2 V−1 s−1 at a low 3 V operating voltage. When the dielectric material is annealed at 350 °C, plasma treatment induces low‐frequency capacitance instability, leading to overestimation of mobility. On the contrary, films annealed at 500 °C show stable capacitance from 1 MHz down to 0.1 Hz. This result highlights the importance of low‐frequency capacitance characterization of solution‐processed dielectrics, especially if plasma treatment is applied before subsequent processing steps. This study progresses metal‐oxide TFT fabrication toward fully inkjet‐printed thin‐film electronics.

Rhodamine 6G and phloxine B as photosensitizers for inkjet-printed indium oxide phototransistors

“…It is plausible that observed greater roughness in the lower temperature treated films due to insufficient thermal energy for complete conversion of precursors from the InO x ink component, resulting in films of insufficiently densified material, with greater porosity than films annealed at a higher temperature. 29 This assertion is supported by observations of InO x ink precursor components in Fourier transform infrared (FTIR) analysis, as described below. The bare R6G dye film was observed to have the greatest roughness of all spin-coated films at 1.97 nm, much higher than the bare PB film of 0.45 nm.…”

“…roughness (all >1.54 nm) than those annealed at 300 °C (all <0.75 nm). It is plausible that observed greater roughness in the lower temperature treated films due to insufficient thermal energy for complete conversion of precursors from the InO x ink component, resulting in films of insufficiently densified material, with greater porosity than films annealed at a higher temperature [29]. This 7 assertion is supported by observations of InO x ink precursor components in Fourier transform infrared (FTIR) analysis, as described below.…”

“…S6cf, ESI †) in tandem with a slight increase in the off current (I off ) for increasing light intensity, in agreement with earlier reports for bare dye on top of oxide semiconductor channel. 29 The least degree of photo-induced change in V on is observed from PB/ InO x composite devices annealed at 300 1C (Fig. S6d, ESI †).…”

“…Blending of In 2 O 3 with organic species has previously been reported for tuning of charge transport properties, both through the organic/In 2 O 3 composite material and as an interfacial layer between stacked material films. [27][28][29][30] Inspired by these earlier reports, the motivation for the dye/InO x composite interlayer approach during this work was to (i) to protect the dye molecules from degradation due to direct exposure to air or mechanical delamination from the semiconductor surface, and (ii) indium oxide content providing atomic similarity, acting to improve interface characteristics such as charge injection to the In 2 O 3 semiconductor channel.…”

Engineering Bilayer AlOx /YAlOx Dielectric Stacks for Hysteresis-Free Switching in Solution-Processed Metal-Oxide Thin-Film Transistors

“…This behavior can be related to the electrolyte behavior of the solution-processed AlO x dielectrics. YAlO x dielectrics have been reported to have minimal to almost no dispersion in their capacitance values at the 0.1 Hz-1 MHz frequency range (Gillan et al, 2021). The permittivity of YAlO x was extracted as 9.1 in our previous study (Bolat et al, 2019).…”