Applied sciences

Opto-Electronics Review

Content

Opto-Electronics Review | 2016 | vol. 24 | No 1 |

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Abstract

In recent years, GaN-based light-emitting diode (LED) has been widely used in various applications, such as RGB lighting system, full-colour display and visible-light communication. However, the internal quantum efficiency (IQE) of green LEDs is significantly lower than that of other visible spectrum LED. This phenomenon is called “green gap”. This paper briefly describes the physical mechanism of the low IQE for InGaN/GaN multiple quantum well (MQW) green LED at first. The IQE of green LED is limited by the defects and the internal electric field in MQW. Subsequently, we discuss the recent progress in improving the IQE of green LED in detail. These strategies can be divided into two categories. Some of these methods were proposed to enhance crystal quality of InGaN/GaN MQW with high In composition and low density of defects by modifying the growth conditions. Other methods focused on increasing electron-hole wave function overlap by eliminating the polarization effect.

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Authors and Affiliations

Q. Zhou
M. Xu
H. Wang
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Abstract

In this paper an analysis of the surface properties of (Ti,Pd,Eu)Ox thin films prepared by magnetron sputtering has been described. In particular, the results of composition and structure investigations were studied in relation to the surface state and optical properties. It was found that (Ti,Pd,Eu)Ox film was nanocrystalline and had a rutile structure. The average crystallites size was equal to 7.8 nm. Films were homogeneous and had densely packed grains. Investigation of the surface properties by XPS showed that titanium was present at 4+ state (in the TiO2form), palladium occurred as PdO2(also at 4+ state), while europium was in Eu2O3form (at 3+ state). In comparison with the unmodiffied TiO2, the coating with Pd and Eu additives had a rather high transparency (approx. 47%) in the visible light range, its optical absorption edge was shifted towards into the longer wavelengths (from 345 nm to 452 nm), and the width of optical energy gap Egopt was nearly twice lower (1.82 eV). Besides, the resistivity of (Ti,Pd,Eu)Ox at room temperature was 1×103 Wcm. In the case of the film as-deposited on Si substrate (p-type) the generation of photocurrent as a response to light beam excitation (λexc = 527 nm) was observed.

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Authors and Affiliations

D. Wojcieszak
D. Kaczmarek
J. Domaradzki
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Abstract

The article presents an overview of polymeric materials for flexible substrates in photovoltaic (PV) structures that could be used as power supply in the personal electronic systems. Four types of polymers have been elected for testing. The first two are the most specialized and heat resistant polyimide films. The third material is transparent polyethylene terephthalate film from the group of polyesters which was proposed as a cheap and commercially available substrate for the technology of photovoltaic cells in a superstrate configuration. The last selected polymeric material is a polysiloxane, which meets the criteria of high elasticity, is temperature resistant and it is also characterized by relatively high transparency in the visible light range. For themost promising of these materials additional studies were performed in order to select those of them which represent the best optical, mechanical and temperature parameters according to their usage for flexible substrates in solar cells.

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Authors and Affiliations

K. Znajdek
M. Sibiński
A. Strąkowska
Z. Lisik
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Abstract

Dye-sensitized solar cells (DSSCs) were prepared using various food dyes. Food dyes are economically superior to organometallic dyes since they are nontoxic and inexpensive. The spectrophotometric evaluation of chosen food dyes in solution and on a TiO2 substrate show that the dyes form J-aggregation on the photoelectrode substrate. Oxidation of potential measurements for used food dyes ensured an energetically permissible and thermodynamically favorable charge transfer throughout the continuous cycle of a photo-electric conversion. The performance of dye-sensitized solar cells based on food dyes was studied. The results illustrate that the dye containing carboxylic acid and sulfonic acid as the acceptor group gave the maximum conversion efficiency 4.20%.

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Authors and Affiliations

M. Hosseinnezhad
S. Rouhani
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Abstract

Non-intentionally doped GaSb epilayers were grown by molecular beam epitaxy (MBE) on highly mismatched semi-insulating GaAs substrate (001) with 2 offcut towards (110). The effects of substrate temperature and the Sb/Ga flux ratio on the crystalline quality, surface morphology and electrical properties were investigated by Nomarski optical microscopy, X-ray diffraction (XRD) and Hall measurements, respectively. Besides, differential Hall was used to investigate the hole concentration behaviour along the GaSb epilayer. It is found that the crystal quality, electrical properties and surface morphology are markedly dependent on the growth temperature and the group V/III flux ratio. Under the optimized parameters, we demonstrate a low hole concentration at very low growth temperature. Unfortunately, the layers grown at low temperature are characterized by wide FWHM and low Hall mobility.

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Authors and Affiliations

D. Benyahia
Ł. Kubiszyn
K. Michalczewski
A. Kębłowski
P. Martyniuk
J. Piotrowski
A. Rogalski

Editorial office

Opto-Electronics Review - Editorial Board

Editor-in-Chief:
L. R. JAROSZEWICZ, Military University of Technology, Warsaw, Poland

Deputy Editor-in Chief:
P. MARTYNIUK, Military University of Technology, Warsaw, Poland


Board of Co-editors:

Optical Design and Applications
V.O. ANGELSKY, Chernivtsi National University, Chernivtsi, Ukraine

Image Processing
M. JÓŹWIK, Warsaw University of Technology, Warsaw, Poland

Metamaterials
T. ANTOSIEWICZ, Warsaw University, Warsaw, Poland

Modelling of Optoelectronic Devices. Semiconductor Lasers
M. DEMS, Łódź Technical University, Łódź, Poland

Optoelectronics Materials
D. DOROSZ, AGH University of Science and Technology, Cracow, Poland

Micro-Opto-Electro-Mechanical Systems
T.P. GOTSZALK, Wrocław University of Technology, Wrocław, Poland

Infrared Physics and Technology <
M. KOPYTKO, Military University of Technology, Warsaw, Poland

Technology and Fabrication of Optoelectronic Devices
J. MUSZALSKI, Institute of Electron Technology, Warsaw, Poland

Photonic Crystals
K. PANAJOTOV, Vrije Universiteit Brussels, Brussels, Belgium

Laser Physics, Technology and Applications
J. ŚWIDERSKI, Warsaw University of Technology, Warsaw, Poland

Optical Sensors and Applications
M. ŚMIETANA, Warsaw University of Technology, Warsaw, Poland

Photovoltaics
A. IWAN, Military Institute of Engineer Technology, Wroclaw, Poland

Biomedical Optics and Photonics
A. LIEBERT, Institute of Biocybernetics and Biomedical Engineering, Warsaw, Poland


International Editorial Advisory Board


D. BIMBERG, Technische Universitaet Berlin, Berlin, Germany

F. CAPASSO, Harvard University, Cambridge, USA

A.I. DIROCHKA, Production Center ORION, Moscow, Russia

P.G. ELISEEV, University of New Mexico, Albuquerque, USA

P. HARING−BOLIVAR, University of Siegen, Siegen, Germany

M. HENINI, University of Nottingham, Nottingham, England

B. JASKORZYNSKA, Royal Institute of Technology, Kista, Sweden

M. KIMATA, Ritsumeikan University, Shiga, Japan

R. KLETTE, University of Auckland, Auckland, New Zealand

S. KRISHNA, University of New Mexico, Albuquerque, USA

H.C. LIU, Shanghai Jiao Tong University, Shanghai, China

J. MISIEWICZ, Wrocław University of Technology, Wrocław, Poland

E. OZBAY, Bilkent University, Ankara, Turkey

J.G. PELLEGRINI, Night Vision and Electronic Sensors Directorate, Fort Belvoir, USA

M. RAZEGHI, Northwestern University, Evanston, USA

A. ROGALSKI, Military University of Technology, Warsaw, Poland

P. RUSSELL, Max Planck Institute for the Science of Light, Erlangen, Germany

V. RYZHII, University of Aizu, Aizu, Japan

C. SIBILIA, Universita' di Roma “La Sapienza”, Roma, Italy

A. TORRICELLI, Politecnico di Milano, Milano, Italy

T. WOLIŃSKI, Warsaw University of Technology, Warsaw, Poland

W. WOLIŃSKI, Warsaw University of Technology, Warsaw, Poland

S.−T. WU, University of Central Florida, Orlando, USA

Y.P. YAKOVLEV, Ioffe Physicotechnical Institute, St. Petersburg, Russia

J. ZIELŃSKI, Military University of Technology, Warsaw, Poland


Language Editor

J. Kulesza, e-mail: jolanta.kulesza@wat.edu.pl


Technical Editors:

R.Podraza, e-mail: renata.podraza@wat.edu.pl

E.Sadowska, e-mail: elzbieta.sadowska@wat.edu.pl

Contact

Military University of Technology,

Gen. Sylwestra Kaliskiego St. 2,

00 – 908 Warsaw, Poland

opelre@wat.edu.pl

Instructions for authors

Open Access policy

Opto-Electronics Review is an open access journal with all content available with no charge for readers in full text version. The journal content is available under the licencse CC BY-SA 4.0

Additional information

Opto-Electronics Review was established in 1992 for the publication of scientific papers concerning optoelectronics and photonics materials, system and signal processing. This journal covers the whole field of theory, experimental verification, techniques and instrumentation and brings together, within one journal, contributions from a wide range of disciplines. Papers covering novel topics extending the frontiers in optoelectronics and photonics are very encourage. The main goal of this magazine is promotion of papers presented by European scientific teams, especially those submitted by important team from Central and Eastern Europe. However, contributions from other parts of the world are by no means excluded.

Articles are published in OPELRE in the following categories:

-invited reviews presenting the current state of the knowledge,

-specialized topics at the forefront of optoelectronics and photonics and their applications,

-refereed research contributions reporting on original scientific or technological achievements,

-conference papers printed in normal issues as invited or contributed papers.

Authors of review papers are encouraged to write articles of relevance to a wide readership including both those established in this field of research and non-specialists working in related areas. Papers considered as “letters” are not published in OPELRE.

Opto-Electronics Review is published quarterly as a journal of the Association of Polish Electrical Engineers (SEP) and Polish Academy of Sciences (PAS) in cooperation with the Military University of Technology and under the auspices of the Polish Optoelectronics Committee of SEP.

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Current Contents - Engineering, Technology & Applied Sciences

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Use of patient images or case details: Studies on patients or volunteers require ethics committee approval and informed consent, which should be documented in the paper.

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