Abstract
Reverse-offset printing (ROP) is a novel printing technique capable of forming electronics-industry-relevant linewidths (≈1 µm) with good thickness control and sharp edge definition. It is demonstrated that through a controlled oxygen-plasma treatment, the energy of the surfaces related to the process steps of ROP can be optimized to allow the patterning of metal-oxide semiconductor layers using a simple printing ink based on metal nitrates dissolved in an organic solvent. The steps of the ROP process are analyzed using surface-energy measurements and Fourier transform infrared spectra of the ink during drying. Thin-film transistors (TFTs) fabricated using a roll-to-plate ROP of In2O3 semiconductor and evaporated Al source/drain (S/D) contacts show, on average, mobilities of 3.1 and 3.5 cm2 V−1 s−1, and ON/OFF-ratios up to 108 and 107 on a Si/SiO2 substrate and on a flexible polyimide-type substrate, respectively. TFTs on the flexible substrate with also the S/D-contacts printed with ROP using Ag nanoparticle ink exhibit a 1.4 cm2 V−1 s−1 mobility. To demonstrate the scalability of the process, continuous lines of In2O3 are printed using a roll-to-roll-compatible (R2R) ROP with linewidths down to ≈2 µm. This process is expected to lead to miniaturized metal-oxide circuits as required by flexible high-resolution sensor arrays and displays.
Original language | English |
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Article number | 1900272 |
Journal | Advanced Electronic Materials |
Volume | 5 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2019 |
MoE publication type | A1 Journal article-refereed |
Funding
VTT's work was funded by the Academy of Finland under grant agreement no. 305450 (project ROXI). Y.K. thanks to JSPS KAKENHI Grant-in-Aid for Young Scientists (B) 17K18410. TOYOBO Co., Ltd. is gratefully acknowledged for the polyimide substrates and ULVAC Inc. for the use of their nanometal ink.
Keywords
- flexible electronics
- metal oxides
- printed transistors
- reverse offset printing