title: Shape-Dependent Multiexciton Emission and Whispering Gallery Modes in Supraparticles of CdSe/Multishell Quantum Dots.
abstract: Semiconductors are indispensable as the active light-emitting element in many optoelectronic devices. However, even the purest bulk semiconductors suffer from considerable nonradiative recombination leading to low photoluminescence efficiencies. Zero-dimensional quantum dots show a much better carrier-to-photon conversion caused by confinement of the excitons but suffer from nonradiative recombination when assembled into a solid, due to exciton energy transfer. Here, we report on the shape-dependent optical properties of self-assembled supraparticles composed of CdSe/multishell nanocrystals. All supraparticles show stable and bright photoluminescence in ambient up to high excitation intensities. When the supraparticles are deposited on a silicon surface their spherical shape is deformed due to drying. In addition to single-exciton emission, we observe bright emission from multiexciton states at high excitation powers. In contrast, supraparticles that retain their perfectly spherical shape show a spectrum with sharp Mie whispering gallery modes, while multiexciton emission is absent.
authors.forename: Daniël
authors.initials: D
authors.lastname: Vanmaekelbergh
authors.forename: Lambert K
authors.initials: LK
authors.lastname: van Vugt
authors.forename: Henriëtte E
authors.initials: HE
authors.lastname: Bakker
authors.forename: Freddy T
authors.initials: FT
authors.lastname: Rabouw
authors.forename: Bart
authors.initials: B
authors.lastname: de Nijs
authors.forename: Relinde J A
authors.initials: RJ
authors.lastname: van Dijk-Moes
authors.forename: Marijn A
authors.initials: MA
authors.lastname: van Huis
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Baesjou
authors.forename: Alfons
authors.initials: A
authors.lastname: van Blaaderen
keywords: Auger recombination; assembly; multiexciton emission; nanocrystal; quantum dot; quantum dot solid; whispering gallery mode