Rationally designed g-C3N4/ZnO nn heterojunction based flexible triboelectric nanogenerators for self-powered temperature sensing application

With the rise in application of Internet of Things (IoT) based wearable gadgets, the scientific community has adopted innumerable strategies to achieve self-powered flexible/wearable sensors. In the present report, we propose the development of triboelectric nanogenerator (TENG) based self-powered flexible temperature sensor comprising of nn heterojunction out of graphitic carbon nitride (g-C3N4) and zinc oxide (ZnO). The novel heterojunction has been developed through occasional infiltration of g-C3N4 flakes in porous ZnO nanostructures via simple chemical route. The triboelectric output in the g-C3N4/ZnO active layer gets drastically enhanced by similar to 60% due to g-C3N4 led modification in dielectric constant and formation of heterojunction interface. Additionally, the generation of electrical output under biomechanical stimuli ensures the efficacy of the TENG for self-powered wearable application. On the other hand, output variation under the influence of temperature, indicates the temperature sensing characteristics of the TENG. Owing to the interface mediated suppression of undesired surface charge annihilation process, the sensitivity of the TENG device is found to be superior for g-C3N4/ZnO based active layer (similar to 0.2 V/degrees C) than bare ZnO (similar to 0.1 V/degrees C). The temperature sensing mechanism and the working range of the sensors have been discussed elaborately in terms of competitive events of thermionic emission and surface charge annihilation. Finally the real-time application of the temperature sensor for distinguishing hot/cold objects and for monitoring human body temperature have been demonstrated.