Efficient tunability of size and optical properties of reduced graphene oxide-ZnO composite nanocrystallites on solid substrates

Growth of ultra-thin luminescent reduced graphene oxide (rGO)-zinc oxide (ZnO) composite nanostructures was accomplished by Langmuir-Blodgett (LB) transfer of GO-Zn composite layers onto solid substrates and subsequent oxidation. Layer structure of LB transferred composites and oxidation procedure determine the size distribution, density, structural order, optical quality of grown ZnO and the extent of GO reduction. Prolonged oxidation (120 min) of composite monolayers produce ZnO nanocrystallites nearly deprived of defects and exhibiting substantially enhanced band edge emission. Prior anchoring of Zn2+ ions on GO layers and oxidation facilitate controlled growth of ZnO nanocrystallites and nanoclusters (20-100 nm), offer tunability of absorption edge (325-355 nm) and assists in amendment of surface defects/band edge emission (376-384 nm). Conductivity of precursor and oxidized composite layers was mapped by recording STM images as well as STS spectra and, the obtained differential conductivity spectra substantiate the changes in GO conductivity and provide range of bandgap values of grown ZnO nanocrystallites (3.1-3.4 eV). The multiple GO-Zn compositing procedures and optimum oxidation conditions introduced in present work facilitate development of rGO-ZnO composite nanostructures with high optical, crystalline quality and conductive characteristics, which pave path for fabrication of such nanostructures for optoelectronic device applications.

Automated summary

The growth of ultra-thin luminescent reduced graphene oxide (rGO)-zinc oxide (ZnO) composite nanostructures was achieved through Langmuir-Blodgett (LB) transfer and subsequent oxidation. The layer structure and oxidation procedure determined the properties of the grown ZnO, such as size distribution, density, structural order, and optical quality. The introduction of specific compositing procedures and optimized oxidation conditions in this work facilitated the development of rGO-ZnO composite nanostructures with high optical, crystalline quality, and conductive characteristics, which is significant for optoelectronic device applications.