Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 6, pp. 886−892.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © F.F. Grekov, B.V. Chernovets, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 6, pp. 945−950.
A Study of Light-Converting Composites Used
in White Light-Emitting Diodes
F. F. Grekov and B. V. Chernovets
St. Petersburg State Polytechnic University, St. Petersburg, Russia
Received June 13, 2013
Abstract—An experimental “wedge” method was suggested for obtaining ample information on the properties
light-converting composites used in light-emitting diodes. The parameter determining the luminous emittance of
the composite layer is the photoluminophore mass in it. It can be optimized experimentally using the suggested
procedure. The composite based on Eu-doped Sialon luminophore upon excitation at a wavelength of 450 nm
exhibits the optimal luminous emittance and emission color at a speciﬁ c load of approximately 5 mg cm
variation of the excitation wavelength in the interval 430–470 nm, the observed trends in the luminous emittance
of the Sialon composites are preserved in a wide interval of concentrations and thicknesses of the composite layer.
The luminous emittance varies in the same direction as the wavelength.
The development of white light-emitting diodes is a
topical technical problem for leading world’s producers
of light sources. It is believed that in the coming years
this type of devices will replace in many ﬁ elds traditional
incandescent and luminescent lamps [1–3].
The most widely used design of white light-emitting
diodes includes an excitation source (gallium nitride
blue light-emitting diode) and a converter of a part of
the emitted blue light to the yellow light, so as to obtain
the total luminous ﬂ ux corresponding to white color. The
converting layer operating in the transmission mode is
a composite of a photoluminophore powder distributed
in a transparent binder. The optical characteristics of the
composite layer exert decisive inﬂ uence on the color and
intensity of the light emitted by the device.
The optical properties of composite layers depend on
many factors, among which we can mention the phase
composition and grain-size distribution of the filler
[4, 5], the binder composition , and the geometric
characteristics of the converting layer . Along with
commercially used cerium-doped yttrium aluminum
garnet [1–3], a traditional photoluminophore for white
light-emitting diodes, europium-doped oxonitride
“Sialon” luminophore, is considered to be the most
promising [8–11]. Efficient luminescence of these
photoluminophores arises at the excitation wavelength λ
of 450 nm, characteristic of industrial blue light-emitting
When developing luminophore layers for white light-
emitting diodes, it is most important to determine such
optical parameters as layer luminous emittance, total
emission spectrum, and energy efﬁ ciency of the light
conversion. Data on these characteristics of layers are
very limited [1–7].
The goal of this study is the development and
implementation of an informative method for studying
optical characteristics of light-converting composites
using a specific object, Sialon composite. To this
end, we chose a binder and an efﬁ cient luminophore,
prepared luminophore layers of various compositions
and thicknesses, and determined the dependence of the
luminous emittance on these parameters under different