A group of researchers from Istituto Italiano di Tecnologia, Politecnico di Milano and Gyeongsang National University has published Nature Communications paper "A sub-150-nanometre-thick and ultraconformable solution-processed all-organic transistor" where they managed to fabricate the first example of ultra-thin fully solution processed organic transistors of thinner than 150 nm and low bending radii, below 0.8 μm.
"Recent advancements in the field of electronics have paved the way to the development of new applications, such as tattoo electronics, where the employment of ultra conformable devices is required, typically achievable with a significant reduction in their total thickness. Organic materials can be considered enablers, owing to the possibility of depositing films with thicknesses at the nanometric scale, even from solution. However, available processes do not allow obtaining devices with thicknesses below hundreds of nanometres, thus setting a limit. Here, we show an all-organic field-effect transistor that is less than 150 nm thick and that is fabricated through a fully solution-based approach. Such unprecedented thickness permits the device to conformally adhere onto nonplanar surfaces, such as human skin, and to be bent to a radius lower than 1 μm, thereby overcoming another limitation for field-effect transistors and representing a fundamental advancement in the field of ultrathin and tattoo electronics."
"Here, we demonstrate that it is possible to fabricate an all solution-processed OFET with a total thickness <150 nm, which is the thinnest freestanding transistor ever fabricated, by adopting an approach based on solution-assisted delamination of free-standing ultrathin insulating poly(vinyl formal) (PVF) layers employed as a self-standing (or self-supporting) gate dielectric. As a consequence, we also demonstrate the smallest bending radius (0.7 µm) reported thus far for any transistor technology. Due to its ultralow thickness, the device shows high transparency, together with an extremely high level of conformability, and is able to confirm on complex 3D surfaces, such as human skin. Such a result pushes even further the boundaries of ultrathin organic electronics towards solution-based and large-area produced imperceptible systems suitable for integration on top of prefabricated objects to make them “smarter” or “connected” without altering their aspect, with simple lamination processes driven by van der Waals forces. In addition to higher mechanical robustness and flexibility, a thinner device implies lower volumes of materials, especially substrates, a critical aspect for the sustainability of electronics conceived to be disposable."
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