Enhanced quantum efficiency in mixed donor-acceptor nanocrystal quantum dot monolayers

Author

Zhang, Xia ; Lunz, Manuela ; Gerard, Valerie A. ; Gun´ko, Yurii K. ; Lesnyak, Vladimir ; Gaponik, Nikolai ; Bradley, A. Louise

Author_Institution

Semicond. Photonics Group, Trinity Coll. Dublin, Dublin, Ireland

fYear

2011

fDate

26-30 June 2011

Firstpage

1

Lastpage

4

Abstract

Colloidal nanocrystal quantum dots have attracted interest for use in light-harvesting and emitting devices. One of the key parameters for such applications is the quantum efficiency. Nanocrystal quantum dots exhibit reduced quantum yield in layers or solids compared with solutions. Optimizing the overall efficiency of the emission is an important goal. Here we report on a large enhancement of the quantum efficiency of mixed TGA-stabilised CdTe quantum dot in closely packed monolayers formed with nanocrystal QDs of two sizes. Energy is transferred from the smaller donor quantum dots to the larger acceptor quantum dots via Förster resonant energy transfer (FRET). The increased quantum efficiency is attributed to exciton recycling from the donor defect states. The acceptor emission enhancement and relative quantum efficiency are strongly dependent on the donor:acceptor concentration ratio. A relative quantum efficiency of 160% is achieved for the mixed quantum dot layer with a donor:acceptor ratio of 11:1.

Keywords

II-VI semiconductors; cadmium compounds; defect states; excitons; impurity states; monolayers; nanophotonics; nanostructured materials; optical materials; photoluminescence; semiconductor quantum dots; CdTe; Forster resonant energy transfer; acceptor quantum dots; colloidal nanocrystal quantum dots; donor defect states; donor quantum dot; exciton recycling; mixed donor-acceptor nanocrystal quantum dot monolayers; photoluminescence; quantum efficiency; Absorption; Energy exchange; Excitons; Nanocrystals; Q measurement; Quantum dots; Recycling; Förster resonant energy transfer; nanocrystal quantum dots; quantum efficiency;

fLanguage

English

Publisher

ieee

Conference_Titel

Transparent Optical Networks (ICTON), 2011 13th International Conference on

Conference_Location

Stockholm

ISSN

2161-2056

Print_ISBN

978-1-4577-0881-7

Electronic_ISBN

2161-2056

Type

conf

DOI

10.1109/ICTON.2011.5971137

Filename

5971137