Laser-induced graphene (LIG) has been utilized as a nonmetallic conductor for the development of various electronics due to its facile, direct, and scalable synthesis process. Here, the graphitization degree of LIG is simply controlled by adjusting the lasing conditions to encode different electronic functionalities such as resistance and capacitance on commercially available papers. The effect of lasing conditions including the number of lasing scans and the lasing power on the graphitization degree of paper-derived LIG is systematically investigated by evaluating the optical, chemical, and electrical properties. The paper-derived LIG with various lasing conditions exhibits a relatively wide sheet resistance range of 61.5 to 9140 Ω sq −1 . The corresponding LIG is used to fabricate resistors and capacitors, and the different electronic functionality encoding is successfully demonstrated by monolithically fabricating nonvolatile read-only memory and resistorcapacitor circuits and verifying the electrical performance of the fabricated devices. This work presents a practical approach to develop paper electronics for cost-effective and environmentally friendly manufacturing.

Poly(4-vinylphenol) (PVP) is a promising gate dielectric material for organic field-effect transistors (OFETs) and circuits fabricated on plastic substrates. Thermal cross-linking of PVP with a cross-linker, such as poly(melamine- co-formaldehyde) methylated (PMF), at a high temperature (above 170 °C) is widely considered an effective method to remove residual hydroxyl groups that induce polarization effects in the dielectric bulk. However, the threshold voltage shift in transfer characteristics is still observed for an OFET with a PVP-PMF dielectric when it is operated at a slow gate voltage sweep rate. The present study examines the cause of the undesired hysteresis phenomenon and suggests a route to enable a reliable operation. We systematically investigate the effect of the PVP-PMF weight ratio and their annealing temperature on the transfer characteristics of OFETs. We discover that the size of the hysteresis is closely related to the concentration of nonhydrogen-bonded hydroxyl groups in the dielectric bulk and this is controlled by the weight ratio. At a ratio of 0.5:1, a complete elimination of hysteresis was observed irrespective of the annealing temperature. We finally demonstrate a highly reliable operation of small-molecule-based OFETs fabricated on a plastic substrate at a low temperature.

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We demonstrate high-performance and stable organic field-effect transistors (OFETs) using parylene-based double-layer gate dielectrics (DLGDs). DLGDs, consisting of parylene C as the upper layer and F as the lower layer, are designed to simultaneously provide good interface and bulk gate dielectric properties by exploiting the advantages of each gate dielectric. The structural effects of DLGDs are systematically investigated by evaluating the electrical characteristics and dielectric properties while varying the thickness ratio of each gate dielectric. The OFET with the optimized DLGD exhibits high performance and operational stability. This systematic approach will be useful for realizing practical electronic applications.