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Materials Congress 2018
Page 49
Nano Research & Applications
ISSN: 2471-9838
W o r l d C o n g r e s s o n
Materials Science & Engineering
A u g u s t 2 3 - 2 5 , 2 0 1 8
Am s t e r d a m , N e t h e r l a n d s
T
his paper aims studying the main reason of ageing of optical materials used
in LED-based products. Solid state lighting (SSL) and more specifically
LEDs, are known to be a revolutionary invention in the lighting industry and are
expected to completely replace traditional less efficient light sources. A solid-
state lighting system is composed of an LED chip with electronic driver(s)
integrated in a package that provides optical functions, thermal management
and/or other functions. White LEDs are multipart systems. Apparently, each
of these components can break and induce failure. Optical degradation
of white LED products is mainly due to the aging of the encapsulants/lens.
Optical degradation of the products is mainly due to the ageing of BPA–PC
encapsulants under Thermal exposure and light radiation. In this study,
BPA–PC plates are aged at different temperatures and light intensities. The
results show that increasing the exposure time leads to the discoloration,
loss of optical properties, decrease of light transmission, and increase in the
yellowing index (YI) of BPA–PC plates leading to a reduction of light intensity
and even early failure before the expected lifetime of the instrument. Reliability
models such as Arrhenius and Eyring equations are used to predict the life
time of the samples at different time. In order to prevent the ageing of BPA-
PC a graphene monolayer has been successfully coated on one side of a
bisphenolA-polycarbonate (BPA-PC) plate, it is shown that graphenemonolayer
considerably increases the lifetime of LEDs mainly by shielding them against
exterior degradation reasons such as moisture and oxygen. This method has
excessive potential to improve the reliability of not only LED-based products
but also many other microelectronics packaging and components, in which
moisture and oxygen are the key causes of failures.
Biography
Maryam Yazdan Mehr did her PhD at Delft University of
Technology from 2011 to till 2015, associated with Professor
Zhang and Professor van Driel in the ECTM group at TU Delft.
During her PhD, she worked on Organic Materials Degradation
in Solid State Applications. During this project, the reliability
and degradation of LEDs was for the first time studied from
both materials and system perspective. One of the greatest
achievements in this project was developing a high accelerated
ageing test methodology. The set-up and the concept are now
being used by Philips Lighting. So far, she has published almost
16 journal papers, more than 10 conference papers, and a book
chapter. After her PhD, she applied for an HTSM grant as a
Post-doc and it was granted in 2016. In June 2017, she started
her Post- doc project entitled Reliability of Optical Materials in
LED-based Products under Harsh Environments in the group of
Professor Zhang at TU Delft.
m.yazdanmehr@tudelft.nlDegradation mechanisms of Bisphenol A Polycarbonate
(BPA-PC) in led-based products
M Yazdan Mehr, W D Van Driel and G Q Zhang
Delft University of Technology, Netherlands
M Yazdan Mehr et al., Nano Res Appl 2018, Volume: 4
DOI: 10.21767/2471-9838-C4-018