A new single/few-layered graphene oxide with a high dielectric constant of 10⁶: contribution of defects and functional groups

Abstract

In this study, we introduce a single/few-layered graphene oxide (GO) synthesized with ultrasonication, and demonstrate its high dielectric permittivity in the frequency range of 20 Hz to 2 MHz and temperature range of 30 C to 180 C. A high dielectric constant of GO ($10 6 ) with low loss was observed at 1 kHz and at 30 C, which is even very high compared to conventional dielectric materials such as CaCu 3 Ti 4 O 12 . The conductivity of our GO was calculated and found to be 3.980 Â 10 À5 to 1.943 Â 10 À5 (DC) and 2.0 Â 10 À3 to 1.7 Â 10 À2 (AC). The various conducting mechanisms governing the conductivity (AC and DC) of GO with varying frequency and temperature are assessed using impedance spectroscopy. The mechanistic approach and the role of functional groups, defects, temperature and frequency are elucidated and discussed with regard to the high dielectric constant. The variation of activation energy from 1.15 (1 kHz) to 0.58 (2.0 MHz) is related to the frequency dependent conductivity of the p-p conjugated electrons and their hopping has also been discussed. The present dielectric results are superior to those of GOL (with fewer defects/less sonication time). Moreover, the present findings suggest that the new GO can be used for scaling advances high performance electronic devices and high dielectric-based electronic and energy storage devices.

Absence of giant dielectric permittivity in graphene oxide materials

“…On the other hand, considering the volume fraction for Milli-Q water, equal to V f ∼0.0361 at a weight fraction of 6.5 wt%, we find a value of 2.3 for the dielectric constant of the GO particles in Milli-Q water. Even if the two values found in Milli-Q water and IPA are just estimates of the dielectric constant of the particle, they are still significantly lower than the giant permittivity found in many other papers [7][8][9][10][11][12][13][14][15]30].…”

“…As stated by the authors, these giant dielectric constants would arise from the orientational polarization of oxygen-containing groups at the surface of GO planes and along the edges [10,11]. Very large permittivities have also been reported for GO based foams and sensors in absence of humidity [11][12][13][14].…”

“…Hong et al drew the same conclusion [8] and Huang et al [9] reported values of relative permittivity above 100 at 100 Hz. Kumar et al have reported even greater values, up to 10 6 at 1 kHz [10].…”

Performance characteristics of guanine incorporated PVDF-HFP/PEO polymer blend electrolytes with binary iodide salts for dye-sensitized solar cells

“…In this study, the higher value of dielectric constant and dielectric loss at lower frequency was observed for guanine incorporated polymer blend electrolyte than the other electrolytes. This indicates that the addition of guanine into polymer blend electrolyte may result in the enhancement of charge carriers along with mobile ions causing higher ionic conductivity [45].…”

Graphene Oxide/Polystyrene Bilayer Gate Dielectrics for Low-Voltage Organic Field-Effect Transistors

“…In particular, graphene derived from graphene oxide (GO), which is referred to as reduced GO (rGO), has attracted much attention for application to flexible devices because of its thinness, excellent electrical properties, and mechanical flexibility [15][16][17]. Most researchers have focused on achieving good electrical properties of rGO; however, it is notable that GO has potential to be used as a gate dielectric layer of OFETs since it possesses insulating properties and a very high k [18][19][20]. Nevertheless, neither the dielectric properties of GO-based materials nor their application as dielectric layers of OFETs has been studied satisfactorily.…”