Plasmon Based Suppression of Surface Trap States and Enhanced Band-Edge Emission Rate in a Single CdTe Quantum Dot

Abstract

Colloidal quantum dots (QDs) have been developed as a versatile photoluminescent and optoelectronic material owning to their size-tunable electronic and optical properties. However, the emission of QDs presents fluorescence intermittency, also known as on/off blinking, Auger recombination and surface traps. QDs surface modification during colloidal synthesis or environmental interaction often creates surface or interfacial trap states that reduce the number and energy of band-edge states (excitonic states) through radiative and non-radiative charge recombination. To minimize surface trap states, Auger recombination and reduce blinking, QDs are typically coated by a ligand or a shell. QDs with thicker shells or core-shell QDs are known to exhibit improved photoluminescence quantum yield of band-edge emission. However, thicker shells isolate the core excitation state and also reduce the near-field interaction between an excitonic state and the photonic environment [1] necessary for different types of applications (e.g. solar cells, light emitting devices, lasers, quantum-photonic devices and so on). Therefore, bare core QDs that have a suppressed surface trap state, an enhanced band-edge state emission with less fluorescence intermittency are indispensable.