Electrically-driven single-photon sources based on colloidal quantum dots with near-optimal antibunching at room temperature

Photonic quantum information requires high-purity, easily accessible, and scalable singlephoton sources. Here, we report an electrically driven single-photon source based on colloidal quantum dots. Our solution-processed devices consist of isolated CdSe/CdS core/shell quantum dots sparsely buried in an insulating layer that is sandwiched between electrontransport and hole-transport layers. The devices generate single photons with near-optimal antibunching at room temperature, i.e., with a second-order temporal correlation function at zero delay (g((2))(0)) being < 0.05 for the best devices without any spectral filtering or background correction. The optimal g((2))(0) from single-dot electroluminescence breaks the lower g((2)()0) limit of the corresponding single-dot photoluminescence. Such highly suppressed multi-photon-emission probability is attributed to both novel device design and carrier injection/recombination dynamics. The device structure prevents background electroluminescence while offering efficient single-dot electroluminescence. A quantitative model is developed to illustrate the carrier injection/recombination dynamics of single-dot electroluminescence.