Decorated Graphene Quantum Dots on “Puckered” Graphene Quantum Sheets for Photosensing Applications

This report shows the cost-effective synthesis of “puckered” graphene quantum sheets (GQSs) decorated by graphene quantum dots (GQDs) utilizing the hydrothermal method. The unique puckered architecture helps the entrapment of incident photons and enhances optoelectronic sensitivity. The decorated GQDs are typically ∼3.9 nm in size, while the GQSs are ∼19 nm thick. The GQDs on the sheets form a connected and uniform layer, enabling improved electron transport across the interface of the light-dependent resistors (LDRs). The enhancement ratio (R<inf>OFF</inf>/R<inf>ON</inf>) of the devices postcoating of puckered GQSs decorated by GQDs is improved by 34% compared to commercial LDRs. The response time is comparable to that of the commercially available LDRs, but the decay time is increased by 61% due to the efficient photon trapping within the puckered layer of GQSs. Experimentally, it has been found that the overall contribution of increased sp² % (83%), reduced ratio of intensity Raman “D” peak/intensity Raman “G” peak (0.04), increased ratio of intensity Raman “2D” peak/intensity Raman “G” peak (0.60), and low work function (4.33 eV) in the puckered GQS decorated by GQDs help to increase photosensitivity. This technique and the unique architecture of two-dimensional sheets are cost-effective for the mass production of photodetectors and coating materials for enhanced light trapping and conversion to electric current. The present work will open avenues for the development of photon detectors used in quantum and semiconducting technologies.