Fotonik Semineri

Macrocrystals of nanocrystals for stable, efficient, and quality lighting

 

Dr. Talha ERDEM
İhsan Doğramacı Bilkent Üniversitesi
Ankara

Abstract:

Starting with the modern times, the lighting applications have become an
essential part of our lives. In parallel with this important place of the
lighting, its share of the total energy consumption reaching ~15% should not
surprise us. Therefore, increasing the efficiencies of the light sources is
of significant importance for a sustainable environment by decreasing the
carbon footprint. At this point, the light-emitting diodes (LEDs) step
forward as the most important candidate for revolutionizing the existing
lighting systems; however, the current conventional technologies, which
employ rare-earth ion based broad-band emitters, are plagued with low
photometric efficiency, lack of light quality, low stability, and
incapability of the spectrum design for application specific performance
optimization.
As a remedy to these problems, we proposed and demonstrated light-emitting
diodes of quantum dots that are efficient narrow-band emitters as opposed to
phosphors 1. To solve the emission stability problem of the quantum dots in
solid-films, we incorporated the quantum dots within crystalline matrices
that act as a barrier against oxygen and humidity and substantially increase
their emission stability 2,3. Another important strength of this technique
has been the preservation of the in-dispersion quantum efficiencies of the
quantum dots in powder form and in solid-films. By employing these material
systems, we designed and successfully demonstrated a warm white LED
exhibiting successful color rendition capability and large spectral overlap
with the human eye sensitivity function.
We also showed that embedding quantum dots into crystalline matrices offers
a robust platform to study the excitonic 4 and plasmonic 5 interactions,
both of which we utilized for increasing the efficiencies of the quantum
dots in crystalline matrices. We believe that the materials and light
sources that we presented here will enable to reach the targets for
realizing high-efficiency and high-stability but also high-quality light
sources for general lighting and displays.

Yer: Fen Fakültesi, Kimya Bölümü, Seminer Salonu
Tarih: 19 Ekim 2016, Çarşamba

Saat: 14:30