Electrically Tunable Enhanced Photoluminescence of Semiconductor Quantum Dots on Graphene

Abstract

Despite the many fascinating discoveries of fundamental significance and device applications involving graphene, one area that has been lacking is graphene-based displays and emissive devices. Since graphene by itself has weak and wavelength-independent absorption and no emission in the visible range, such devices must rely on synergistic combination with other highly sensitive optical materials such as quantum dots. However, the well-known strong nonradiative energy transfer between emitters and quantum dots and graphene makes it impossible to create such devices due to strong emission quenching. Here we report the first demonstration of enhanced photoluminescence of quantum dots in close proximity to graphene field effect transistor devices, which are electrically and spectrally tunable. The enhanced emission originates from super-radiance between closely packed quantum dots placed close to single-layer graphene, which overcomes the strong nonradiative quenching observed earlier. Finite difference time domain simulations shed light on the regime in which such effects are likely to dominate. Our work opens up new avenues for research on novel displays, lasers, and emissive devices involving graphene–quantum dot hybrids as well as to study fundamental aspects of electrically tunable light–matter interactions at the nanoscale.