Investigation of charge transport mechanism in hydrothermally synthesized reduced graphene oxide (rGO) incorporated zinc oxide (ZnO) nanocomposite films

Abstract

The present study aims to investigate the impact of reduced graphene oxide (rGO) incorporation on the charge transport properties of zinc oxide (ZnO) nanocomposite films. ZnO and varied weight percentage of rGO (1.25% to 10%) in ZnO-rGO nanocomposites are synthesized via cost-effective and facile hydrothermal method. The effect of varying weight percentage of rGO in ZnO nanocomposite is analysed by techniques such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Fourier transform infra-red spectroscopy (FTIR), and Raman spectroscopy. The observed current-voltage (I-V) characteristics at room temperature show the enhancement in forward current with an increasing weight percentage of rGO (1.25% to 10%) in ZnO nanocomposite films. To study the charge transport mechanism in nanocomposite films, dual-logarithmic I-V characteristics are plotted. From the characteristic curves, we find that three different laws of space charge limited conduction (SCLC) model namely Ohm's law, Child's law, and trap-limited SCLC mechanism describe charge transport properties in the ZnO-rGO nanocomposite films. At a low weight percentage of rGO (1.25%) in ZnO-rGO nanocomposite films, a transition from Child's law to trap-limited SCLC mechanism (0.9 V being the cross-over voltage) is obtained. As the weight percentage of rGO in ZnO-rGO nanocomposite films is increased from 2.5 to 10%, the conduction is favored by Ohm's law at low applied voltages to Child's law at higher applied voltages. Best experimental results are shown with 5% of rGO in ZnO-rGO nanocomposite. The prepared nanocomposite films have potential applications in UV-photodetector devices.

A proposed device based on MoSe2-ZnO heterojunctions on rGO for enhanced ethanol gas sensing performances at room temperature

“…Additionally, within the range of 1000-750 cm −1 peaks are observed corresponding to Mo-O bonds, while the peak at 464 cm −1 corresponds to Se-O-Se bonds [50,51]. Peaks in the FTIR spectrum of ZnO are observed corresponding to O-H (3427 cm −1 ), COOH (1510-1380 cm −1 ), Zn-OH (836 cm −1 ), and Zn-O (510 and 370 cm −1 ) [35]. The FTIR spectrum of GO reveals several distinctive peaks: a broad peak at 3280 cm −1 is attributed to O-H groups, and peaks at 1700 and 1562 cm −1 indicate C=O and C=C stretching, respectively.…”

“…A hydrothermal approach was utilized to synthesize MoSe 2 /ZnO/rGO nanocomposite. MoSe 2 nanosheets and ZnO nanorods were synthesized using a hydrothermal method while GO nanosheets were synthesized via a modified Hummer's method as reported earlier in our previous work [3,28,35,36].…”

“…The FTIR spectrum of GO reveals several distinctive peaks: a broad peak at 3280 cm −1 is attributed to O-H groups, and peaks at 1700 and 1562 cm −1 indicate C=O and C=C stretching, respectively. Additionally, a minor peak at 1400 cm −1 corresponds to O-H deformation, while two peaks at 1215 and 1030 cm −1 correspond to epoxy C-O-C and alkoxy C-O stretching vibrations, respectively [35,52]. The spectrum of ternary MoSe 2 /ZnO/rGO nanocomposite displays the peak corresponding to Mo-O bonds, and Zn-O bonds.…”

Perspective Coatings Based on Structured Conducting ITO Thin Films for General Optoelectronic Applications

“…Moreover, it will be important to compare the ITO with CNTs and, for example, ZnO conducting coating structures with CNTs as well. ZnO has arguably been effectively studied [62][63][64][65][66] due to the reason that any surface modification can change the wettability, photocatalytic, and optical properties of the ZnO matrix with a good advantage. It would be useful to introduce it to the CNTs on the surface of the matrix ZnO materials and compare the results with that obtained for the ITO structured with CNTs.…”