Multi-emissive graphene oxide quantum dots with remarkable pH-responsive long-wavelength emission

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Graphene oxide quantum dots (GOQDs) are derived from graphene oxide (GO) nanosheets.
• Understanding the photophysical properties of GOQDs is crucial for their application.

Purpose of the Study:

• To synthesize GOQDs via oxidative cutting of GO nanosheets.
• To investigate the pH-dependent photoluminescence of GOQDs.
• To explore the potential of GOQDs in white light-emitting applications.

Main Methods:

• Oxidative cutting of graphene oxide (GO) nanosheets to produce graphene oxide quantum dots (GOQDs).
• Characterization of GOQD photoluminescence across a range of pH values.
• Fabrication of polyvinyl alcohol (PVA)-GOQD films for LED applications.

Main Results:

• GOQDs exhibit pH-dependent emission, with green/yellow light in acidic/neutral conditions and orange-red light at pH 12.8.
• Aggregation mechanisms of GOQDs differ between acidic (H-bond) and alkaline (donor-acceptor) conditions.
• Cations quench orange-red emission, while PVA-GOQD films produce white light (CIE: (0.336, 0.388), CRI: 85, CCT: 5160 K) with good photostability.

Conclusions:

• GOQDs display tunable photoluminescence properties influenced by pH and aggregation state.
• PVA-GOQD films demonstrate potential as efficient and stable photoemissive layers for white light-emitting diodes (LEDs).