Reduced graphene oxide based temperature sensor: Extraordinary performance governed by lattice dynamics assisted carrier transport

In this article, we report the sensing performance of reduced graphene oxide (rGO) based resistive type temperature sensor fabricated by spin coating. A detailed analysis is presented for understanding the combined effect of lattice vibrational properties and temperature dependent electrical conductivity while considering charge carrier scattering with phonons, impurities, defects, and edge boundaries of rGO flakes. The purpose of this analysis is to find out how together they influence the temperature coefficient of resistance (TCR) and thermal hysteresis (HTh) of rGO based films. TCR and Hth are the core factors for efficient operation of a temperature sensor as these govern important sensing characteristics such as sensitivity, resolution, drift, response- and recovery-time. Experimental results show that the proposed sensor exhibits TCR ∼ −0.801%/K (in 303K-373K) and negligible thermal hysteresis (∼0.7%) resulting in high resolution (∼0.1 K), response- and recovery-time of ∼52 s and ∼285 s respectively. Besides, TCR and Hth are also found to depend on rGO concentration and working temperature range of sensors. By lowering the sensing temperature range to 303K-77K region, TCR was found to increase abruptly from −0.801%/K to −32.04%/K. All this optimized data were obtained for the sensor with 3 wt.% of rGO. Dynamic plot shows its sensitivity to respond to even ∼0.1 K change in temperature. Cyclic testing demonstrates good stability in 77K-573K temperature range with negligible drift. These studies are significant towards the fabrication of simple, highly sensitive, and cost effective temperature sensor with high reproducibility. There is still enough room to improve TCR of rGO based sensors through synthesis, advanced sensor design and development; higher TCR will definitely lead to far better temperature sensing performance as theory predicts.