Implementation of high-quality warm-white light-emitting diodes by a model-experimental feedback approach using quantum dot-salt mixed crystals
Author(s)
Date
2015Source Title
ACS Applied Materials and Interfaces
Print ISSN
1944-8244
Publisher
American Chemical Society
Volume
7
Issue
41
Pages
23364 - 23371
Language
English
Type
ArticleItem Usage Stats
255
views
views
289
downloads
downloads
Abstract
In this work, a model-experimental feedback approach is developed and applied to fabricate high-quality, warm-white light-emitting diodes based on quantum dots (QDs) as color-conversion materials. Owing to their unique chemical and physical properties, QDs offer huge potential for lighting applications. Nevertheless, both emission stability and processability of the QDs are limited upon usage from solution. Incorporating them into a solid ionic matrix overcomes both of these drawbacks, while preserving the initial optical properties. Here borax (Na2B4O7·10H2O) is used as a host matrix because of its lower solubility and thereby reduced ionic strength in water in comparison with NaCl. This guarantees the stability of high-quality CdSe/ZnS QDs in the aqueous phase during crystallization and results in a 3.4 times higher loading amount of QDs within the borax crystals compared to NaCl. All steps from the synthesis via mixed crystal preparation to the warm-white LED preparation are verified by applying the model-experimental feedback, in which experimental data and numerical results provide feedback to each other recursively. These measures are taken to ensure a high luminous efficacy of optical radiation (LER) and a high color rendering index (CRI) of the final device as well as a correlated color temperature (CCT) comparable to an incandescent bulb. By doing so, a warm-white LED with a LER of 341 lm/Wopt, a CCT of 2720 K and a CRI of 91.1 is produced. Finally, we show that the emission stability of the QDs within the borax crystals on LEDs driven at high currents is significantly improved. These findings indicate that the proposed warm-white light-emitting diodes based on QDs-in-borax hold great promise for quality lighting. © 2015 American Chemical Society.
Keywords
Colloidal nanocrystalsColor conversion
Composites
Mixed crystals
Quantum dots
White LEDs
Borate minerals
Color
Composite materials
Diodes
Ionic strength
Lighting
Nanocrystals
Optical properties
Semiconductor quantum dots
Sodium borate
Chemical and physical properties
Colloidal nanocrystals
Color conversions
Correlated color temperature
High color rendering index
Mixed crystals
White LED
White light emitting diodes
Light emitting diodes
Permalink
http://hdl.handle.net/11693/26685Published Version (Please cite this version)
http://dx.doi.org/10.1021/acsami.5b08377Collections
Related items
Showing items related by title, author, creator and subject.
-
A photometric investigation of ultra-efficient LEDs with high color rendering index and high luminous efficacy employing nanocrystal quantum dot luminophores
Erdem, T.; Nizamoglu, S.; Sun, X. W.; Demir, Hilmi Volkan (Optical Society of America, 2009-12-24)We report a photometric study of ultra-efficient light emitting diodes (LEDs) that exhibit superior color rendering index (CRI) and luminous efficacy of optical radiation (LER) using semiconductor quantum dot nanocrystal ... -
Color in interior spaces
Demirörs, Müge Bozbeyli (Bilkent University, 1992)Color can be approached from different perspectives and disciplines such as, biology, theory, technology, and psychology. This thesis discusses color, from the stand point of interior spaces, which to some extent involves ... -
A histogram-based approach for object-based query-by-shape-and-color in image and video databases
Şaykol, E.; Güdükbay, Uğur; Ulusoy, Özgür (Elsevier, 2005)Considering the fact that querying by low-level object features is essential in image and video data, an efficient approach for querying and retrieval by shape and color is proposed. The approach employs three specialized ...