Semi-transparent reduced graphene oxide temperature sensor on organic light-emitting diodes for fingerprint liveness detection of smartphone authentication

초록

We report a semi-transparent temperature sensor for fingerprint liveness detection on an organic light-emitting diode (OLED). Solution-processable graphene oxide was coated between two indium tin oxide electrodes on a glass substrate, and a semi-transparent reduced graphene oxide (rGO) temperature sensor was successively fabricated through graphene oxide (GO) reduction using a laser source. The rGO temperature sensor showed a resistance variance characteristic of 80 % compared to the initial resistance when heated from 15 °C to 170 °C. When finger was touched on the rGO temperature sensor, the resistance variation was 0.5 % and 7 % at 35 °C and 50 °C, respectively. In addition, GO was coated on the light-emitting side of green phosphorescent OLEDs to investigate the damage caused by photothermal reduction energy. The OLEDs irradiated by the laser source for GO reduction showed nearly the same current–voltage characteristics and electroluminescence spectrum as the device without laser irradiation, although the luminance of the device decreased due to the absorption of rGO. © 2021 Elsevier B.V.

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