Flexible and transparent thermistors fabricated by controlled Langmuir-Blodgett assembly of monolayer graphene flakes

초록

The growing demand for wearable devices has increased the need for flexible, transparent temperature sensors. However, current limitations in flexible materials and fabrication processes pose significant challenges. In this study, we propose a monolayer graphene-based sensor fabricated by Langmuir-Blodgett (LB) deposition. Transparent and flexible thermistors were constructed by assembling monolayer graphene oxide flakes on a polymer substrate using the LB technique, followed by vapor-phase reduction. Controlling the surface pressure during the LB assembly tuned the electronic transport properties of the reduced graphene oxide (rGO) film, enhancing the temperature sensitivity. The assembled monolayer rGO film exhibited a superior temperature coefficient of resistance of -1.41 +/- 0.02%/degrees C over a temperature range of 30-110 degrees C. The thermistor demonstrated an optical transmittance of 91.9% at a wavelength of 550 nm, as well as a small critical bending radius of 3.72 mm, due to its atomically thin structure. In addition, it exhibited high temperature resolution and outstanding stability under repeated bending. The proposed sensor detected minute temperature changes, enabling real-time temperature monitoring of various objects. This study presents a viable approach for fabricating flexible and transparent temperature sensors through the controlled assembly of graphene flakes.

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