A Low-Temperature Efficient Approach for the Fabrication of ZnO-rGO heterostructures for Applications in Optoelectronic Applications

In recent years, graphene oxides (GO)/reduced graphene oxide (rGO) and its derivatives have garnered/gained the attention of the scientific and research community due to their superior candidature in various electronic and optoelectronic devices due to their exceptional solution processability, easy fabrication, and tunable electron transport properties. However, the requirement of high-temperature processing steps and complicated processes motivates the scientific community to find simple, efficient, and low-temperature methods. Here, we report the synthesis of GO/rGOs and ZnO-rGO nanocomposite at a relatively low temperature of 150 °C using a simple and efficient solution-processed methodology. The SEM/EDX, XRD, Raman spectroscopy, FTIR, and UV-vis spectroscopy performed to investigate the morphological, structural, and optical properties confirmed the successful synthesis of GO, rGO, and ZnO-rGO with an enhanced carbon-carbon (sp2 and sp
$^{3}$
) component and reduced oxygen-containing functional group and the restoration of the graphitic domain in the hybrid nanocomposite, attributed to the possible chemical interaction between the rGO and ZnO through oxygen-containing functional groups. The bandgap of ZnO-rGO is modulated from 3.27 eV to 2.72 eV in comparison to pure ZnO. Using Hall measurement the carrier concentration was found to be
$3.077\times 10^{17}$
cm
$^{-3}$
,
$4.518\times 10^{20}$
cm
$^{-3}$
, and
$2.973\times 10^{19}$
cm
$^{-3}$
for ZnO, rGO, and ZnO-rGO, respectively, and the mobility was calculated as 16.787 cm2/V.s, 46.112 cm2/V.s and 25.953 cm2/V.s, respectively. The fabricated cell exhibited a power conversion efficiency of 6.17 % (
$\text{V}_{\mathrm {oc}}$
= 0.551 V and
$\text{J}_{\mathrm {sc}}$
= 24.33 mA/cm2. After 8 weeks, 90 % of the initial efficiency could be achieved, suggesting excellent stability of the fabricated devices. The prepared samples have potential applications in different electronics and optoelectronics devices for enhanced performance.