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Origins of Low Quantum Efficiencies in Quantum Dot LEDs
Author(s) -
Bozyigit Deniz,
Yarema Olesya,
Wood Vanessa
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201203191
Subject(s) - quantum dot , light emitting diode , materials science , auger effect , photoluminescence , optoelectronics , luminescence , electric field , nanocrystal , quenching (fluorescence) , spontaneous emission , electroluminescence , carrier generation and recombination , auger , nanotechnology , fluorescence , semiconductor , atomic physics , physics , optics , laser , quantum mechanics , layer (electronics)
The promise for next generation light‐emitting device (LED) technologies is a major driver for research on nanocrystal quantum dots (QDs). The low efficiencies of current QD‐LEDs are often attributed to luminescence quenching of charged QDs through Auger‐processes. Although new QD chemistries successfully suppress Auger recombination, high performance QD‐LEDs with these materials have yet to be demonstrated. Here, QD‐LED performance is shown to be significantly limited by the electric field. Experimental field‐dependent photoluminescence decay studies and tight‐binding simulations are used to show that independent of charging, the electric field can strongly quench the luminescence of QD solids by reducing the electron and hole wavefunction overlap, thereby lowering the radiative recombination rate. Quantifying this effect for a series of CdSe/CdS QD solids reveals a strong dependence on the QD band structure, which enables the outline of clear design strategies for QD materials and device architectures to improve QD‐LED performance.