Metal oxide (MO) semiconductor thin films prepared from solution typically require multiple hours of thermal annealing to achieve optimal lattice densification, efficient charge transport, and stable device operation, presenting a major barrier to roll-to-roll manufacturing. Here, we report a highly efficient, cofuel-assisted scalable combustion blade-coating (CBC) process for MO film growth, which involves introducing both a fluorinated fuel and a preannealing step to remove deleterious organic contaminants and promote complete combustion. Ultrafast reaction and metal–oxygen–metal (M-O-M) lattice condensation then occur within 10–60 s at 200–350 °C for representative MO semiconductor [indium oxide (In2O3), indium-zinc oxide (IZO), indium-gallium-zinc oxide (IGZO)] and dielectric [aluminum oxide (Al2O3)] films. Thus, wafer-scale CBC fabrication of IGZO-Al2O3thin-film transistors (TFTs) (60-s annealing) with field-effect mobilities as high as ∼25 cm2V−1s−1and negligible threshold voltage deterioration in a demanding 4,000-s bias stress test are realized. Combined with polymer dielectrics, the CBC-derived IGZO TFTs on polyimide substrates exhibit high flexibility when bent to a 3-mm radius, with performance bending stability over 1,000 cycles.
Polyetherimides (PEI) are high‐performance thermoplastic polymers featuring a high dielectric constant and excellent thermal stability. In particular, PEI thin films are of increasing interest for use in solid‐state capacitors and membranes, yet the cost and thickness are limited by conventional synthesis and thermal drawing techniques. Here, a method of synthesizing ultrathin PEI films and coatings is introduced based on interfacial polymerization (IP) of poly(amic acid), followed by thermal imidization. Control of transport, reaction, and precipitation kinetics enables tailoring of PEI film morphology from a nanometer‐scale smooth film to a porous micrometer‐scale layer of polymer microparticles. At short reaction times (≈1 min) freestanding films are formed with ≈1 µm thickness, which to our knowledge surpass commercial state‐of‐the‐art films (3–5 µm minimum thickness) made by thermal drawing. PEI films synthesized via the IP route have thermal and optical properties on par with conventional PEI. The use of the final PEI is demonstrated in structurally colored films, dielectric layers in capacitors, and show that the IP route can form nanometer‐scale coatings on carbon nanotubes. The rapid film formation rate and fine property control are attractive for scale‐up, and established methods for roll‐to‐roll processing can be applied in future work.
more » « less- NSF-PAR ID:
- 10400659
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 33
- Issue:
- 24
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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