Reduced graphene oxide (rGO) based wideband optical sensor and the role of Temperature, Defect States and Quantum Efficiency

Abstract

We report a facile and cost-effective approach to develop self-standing reduced Graphene Oxide (rGO) film based optical sensor and its low-temperature performance analysis where midgap defect states play a key role in tuning the crucial sensor parameters. Graphite oxide (GO) is produced by modified Hummers’ method and reduced thermally at 250 °C for 1 h in Argon atmosphere to obtain rGO. Self-standing rGO film is prepared via vacuum filtration. The developed film is characterized by HRTEM, FESEM, Raman, and XRD techniques. The developed sensor exhibits highest sensitivity towards 635 nm illumination wavelength, irrespective of the operating temperature. For a given excitation wavelength, photoresponse study at low temperature (123K–303K) reveals inverse relationship between sensitivity and operating temperature. Highest sensitivity of 49.2% is obtained at 123 K for 635 nm laser at power density of 1.4 mW/mm2. Unlike sensitivity, response- and recovery-time demonstrate directly proportional dependence with operating temperature. Power dependent studies establish linear relation between power-density and sensitivity, and a safe limit beyond which sample heating prolongs the recovery time. Wavelength-dependent studies shows that proposed sensor can efficiently operate from visible to near NIR region. To the best of our knowledge such rGO based optical sensor performance at low temperature had not been reported earlier.

Electrical transport properties and ultrafast optical nonlinearity of rGO–metal chalcogenide ensembles

“…Also electronelectron scattering increases as temperature increases. 49,50 With increase in different scattering factors, transit time (average time taken by charge carriers to travel from one electrode to the other) will be increased. This leads to a decrease in the charge collection rate at the electrode 51 and consequently, photosensitivity decreases with increase in temperature.…”

Photocatalytic treatment of tannery wastewater using reduced graphene oxide and CdS/ZnO to produce hydrogen with simultaneous sulfide abatement

“…In addition to the increasing ratio I D /I G compared to the ratio for GO [58], a sp 3 /sp 2 ratio reflex, it is possible to observe a small redshift in the G band, from 1599 to 1582 cm −1 , especially for the highest performance photocatalysts, RGO/(Zn/Cd0.4-IE) and RGO/(Zn/Cd1.5-IE). This result is indicative of the restoration of the C=C sp 2 bond [59,60], as found in the graphene hexagonal lattice.…”

An ultrafast quantum thermometer from graphene quantum dots

“…Transformation of graphite to graphene oxide (GO) via a chemical conversion technique has surfaced as a convenient method to produce graphene like monolayers with considerable yield. 51,52,55 Modied Hummers' method based oxidative treatment of natural graphite akes was performed to prepare graphite oxide. 56 Unlike pristine graphite, GO is highly oxidized having oxygenated epoxide bonds on the basal plane, whereas carbonyl and carboxyl groups are present at the sheet edges.…”

“…[41][42][43] Although a substantial amount of work has been done on the carrier transport mechanism in graphene, 17,38,[44][45][46][47][48] hardly any studies are available on the development of temperature sensors either from graphene or GQD arrays, exploiting their carrier transport properties. In the case of carrier transport in graphene or 2D materials, the current ow is controlled by scattering events; [49][50][51][52] whereas in GQDs, the current will exist only if carriers overcome the Coulomb blockade potential. 53,54 The temperature dependent differential change in resistance/current in the circuit is the key factor for the development of a highly sensitive temperature sensor.…”