Red organic light-emitting diodes with high efficiency, low driving voltage and saturated red color realized via two step energy transfer based on ADN and Alq3 co-host system

Khizar-ul Haq,Liu Shan-peng,M.A. Khan,X.Y. Jiang,Z.L. Zhang,Jin Cao,W.Q. Zhu 한국물리학회 2009 Current Applied Physics Vol.9 No.1

We demonstrated efficient red organic light-emitting diodes based on a wide band gap material 9,10-bis(2-naphthyl)anthracene (ADN) doped with 4-(dicyano-methylene)-2-t-butyle-6-(1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10(2-benzothiazolyl)quinolizine-[9,9a,1gh]coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA)/ N,N'-bis(naphthalene-1-yl)-N,N0-diphenyl-benzidine (NPB)/[ADN:Alq3]:DCJTB:C545T/Alq3/LiF/Al. It was found that C545T dopant did not by itself emit but did assist the energy transfer from the host (ADN) to the red emitting dopant via cascade energy transfer mechanism. The OLEDs realized by this approach significantly improved the EL efficiency. We achieved a significant improvement regarding saturated red color when a polar co-host emitter (Alq3) was incorporated in the matrix of [ADN:Alq3]. Since ADN possesses a considerable high electron mobility of 3.1 × 10-4 ㎠ V-1 s-1, co-host devices with high concentration of ADN (>70%) exhibited low driving voltage and high current efficiency as compared to the devices without ADN. We obtained a device with a current efficiency of 3.6 cd/A, Commission International d’Eclairage coordinates of [0.618, 0.373] and peak λmax = 620 nm at a current density of 20 mA/㎠. This is a promising way of utilizing wide band gap material as the host to make red OLEDs, which will be useful in improving the electroluminescent performance of devices and simplifying the process of fabricating full color OLEDs. We demonstrated efficient red organic light-emitting diodes based on a wide band gap material 9,10-bis(2-naphthyl)anthracene (ADN) doped with 4-(dicyano-methylene)-2-t-butyle-6-(1,1,7,7-tetramethyl-julolidyl-9-enyl)-4H-pyran (DCJTB) as a red dopant and 2,3,6,7-tetrahydro-1,1,7,7,-tetramethyl-1H,5H,11H-10(2-benzothiazolyl)quinolizine-[9,9a,1gh]coumarin (C545T) as an assistant dopant. The typical device structure was glass substrate/ITO/4,4',4''-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA)/ N,N'-bis(naphthalene-1-yl)-N,N0-diphenyl-benzidine (NPB)/[ADN:Alq3]:DCJTB:C545T/Alq3/LiF/Al. It was found that C545T dopant did not by itself emit but did assist the energy transfer from the host (ADN) to the red emitting dopant via cascade energy transfer mechanism. The OLEDs realized by this approach significantly improved the EL efficiency. We achieved a significant improvement regarding saturated red color when a polar co-host emitter (Alq3) was incorporated in the matrix of [ADN:Alq3]. Since ADN possesses a considerable high electron mobility of 3.1 × 10-4 ㎠ V-1 s-1, co-host devices with high concentration of ADN (>70%) exhibited low driving voltage and high current efficiency as compared to the devices without ADN. We obtained a device with a current efficiency of 3.6 cd/A, Commission International d’Eclairage coordinates of [0.618, 0.373] and peak λmax = 620 nm at a current density of 20 mA/㎠. This is a promising way of utilizing wide band gap material as the host to make red OLEDs, which will be useful in improving the electroluminescent performance of devices and simplifying the process of fabricating full color OLEDs.

A proton induced X-ray emission (PIXE) analysis of concentration of major/trace and toxic elements in broiler gizzard and flesh of Tehsil Gujar Khan area in Pakistan

Khawar Nadeem,Javaid Hussain,Noaman Ul Haq,A. Ul Haq,Waheed Akram,Ishaq Ahmad 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.8

Ten gizzard and three flesh samples of the broiler were collected from different locations in Tehsil Gujar Khan District Rawalpindi, Pakistan. The samples were dried, crushed and ground. Pellets were prepared by pressing the powder of the samples and that of the Bovine liver 1577c reference material obtained from NIST, USA. Proton induced X-ray emission (PIXE) installed at National Center for Physics, Islamabad, Pakistan has been used as a reliable and improved technique to determine concentration of various major/trace and toxic elements e.g. S, Cl, K, Ca, Cl, Fe, Cu, Mn, Co, Zn, Ti, Cd, Ga, Cr, V and Ni, in the Gizzard and Flesh samples of the broiler. The concentrations of all the detected elements in the samples are statistically significant. The certified and measured values of the elements in the reference material were in agreement with each other within a deviation of 7%. S, Cl, K and Ca are within tolerable limits and are good for human consumption. Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn were more than the acceptable limits of World Health Organization, WHO whereas Ga, As, Sn, Sb and Pb are not detected in most of the samples.

Engineering of highly mismatched alloy with semiconductor and semi-metallic substituent's for photovoltaic applications

Haq, Bakhtiar Ul,Ahmed, R.,Mohamad, Mazmira,Shaari, A.,Rhee, JooYull,AlFaify, S.,Kanoun, Mohammed Benali,Goumri-Said, Souraya ELSEVIER 2017 Current Applied Physics Vol.17 No.2

<P>Highly mismatched alloys (HMAs) are getting a substantial interest of researchers because of holding competence of rapid change in physical properties with minor compositional change and consequently showing their potential for solar energy and photovoltaic applications. In the present density functional theory based work, we design HMAs from the extremely dissimilar GaP (semiconductor) and GaBi (semi metal). The alloying of the two compounds with unmatched electronic characteristics has triggered a rapid reduction in the energy gap of GaPBi. The energy gap is reduced by 39.3 meV for every 1% increase in Bi composition. The semiconductor behavior of GaPBi based HMAs is found to be transformed to semi metallic for replacing 64.6% of P atoms by Bi. Unlike the conventional alloys, the variation in the electronic energy gap of GaP1-xBix shows deviation from the Vegard's formalism. Where the optical properties are strongly influenced with the narrowing energy gap of GaPBi. For the Bi-rich GaPBi, the notable red shift is observed in optical dielectric function and absorption spectra. Moreover, the larger atomic size of Bi has enhanced the lattice parameters of Bi-rich GaPBi. The GaPBi based HMAs with tunable energy gap in the span of 2.51 eV-0 eV and the interesting optical properties highlight them prospective materials for optoelectronic applications. (C) 2016 Elsevier B.V. All rights reserved.</P>

Composition-induced influence on the electronic band structure, optical and thermoelectric coefficients of the highly mismatched GaNSb alloy over the entire range: A DFT analysis

Ul Haq, Bakhtiar,Ahmed, R.,Rhee, Joo Yull,Shaari, A.,AlFaify, S.,Ahmed, M. Elsevier 2017 Journal of alloys and compounds Vol.693 No.-

<P><B>Abstract</B></P> <P>Capable of achieving wide control over energy band gap and following optoelectronic properties; the highly mismatched alloys (HMAs) are considered to be promising materials for solar energy conversion devices. The dramatic restructuring of energy bands and density of states in HMAs caused by the replacement of anions with distinctly-mismatched isovalent constituents could further be an important course in improving their thermoelectric efficiency. In this paper, we attempt to explore and address the composition-induced modifications in the electronic band structure and the resultant effects on optical spectra and thermoelectric coefficients of GaN<SUB>1−x</SUB>Sb<SUB>x</SUB> based HMAs in the framework of density functional theory. We observe, the substitution of N by Sb, considerably affects its band structure and split the conduction band minimum (CBM) into sub-bands. With increasing Sb composition, the lowest sub-band stemmed from N-s electrons has experienced drastic downward shift leading to energy gap narrowing. Interestingly, the energy gap narrowing along R- Γ is found to be faster than that of Γ- Γ point leading to an amazing direct to indirect band gap crossover. On the other hand, the composition-induced energy gap narrowing stimulates the red-shift in fundamental absorption edge in both ultraviolet and the infrared regime, making the GaNSb potentially useful material for photovoltaic applications. In addition, substantial effect on the thermoelectric coefficients of GaNSb is also observed via Sb substitution. We obtain larger Seebeck coefficient, improved power factors and figure of merit (ZT) for GaNSb at low Sb substitution and found diminishing effect with the further increase of Sb composition. With enhanced Seebeck coefficient, power factor and ZT values at modest doping levels, GaNSb alloy could be a promising candidate for near or above room temperature thermoelectric applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Alloying of GaNSb across entire composition in the framework of DFT. </LI> <LI> The striking direct to indirect energy gap cross over. </LI> <LI> Enhanced absorption in ultraviolet, visible and infrared energy regime. </LI> <LI> Comprehensive investigations of thermoelectric properties of GaNSb alloy. </LI> </UL> </P>

Engineering of highly mismatched alloy with semiconductor and semi-metallic substituent's for photovoltaic applications

Bakhtiar Ul Haq,R. Ahmed,Mazmira Mohamad,A. Shaari,이주열,S. AlFaify,Mohammed Benali Kanoun,Souraya Goumri-Said 한국물리학회 2017 Current Applied Physics Vol.17 No.2

Highly mismatched alloys (HMAs) are getting a substantial interest of researchers because of holding competence of rapid change in physical properties with minor compositional change and consequently showing their potential for solar energy and photovoltaic applications. In the present density functional theory based work, we design HMAs from the extremely dissimilar GaP (semiconductor) and GaBi (semimetal). The alloying of the two compounds with unmatched electronic characteristics has triggered a rapid reduction in the energy gap of GaPBi. The energy gap is reduced by 39.3 meV for every 1% increase in Bi composition. The semiconductor behavior of GaPBi based HMAs is found to be transformed to semimetallic for replacing 64.6% of P atoms by Bi. Unlike the conventional alloys, the variation in the electronic energy gap of GaP1-xBix shows deviation from the Vegard's formalism. Where the optical properties are strongly influenced with the narrowing energy gap of GaPBi. For the Bi-rich GaPBi, the notable red shift is observed in optical dielectric function and absorption spectra. Moreover, the larger atomic size of Bi has enhanced the lattice parameters of Bi-rich GaPBi. The GaPBi based HMAs with tunable energy gap in the span of 2.51 eVe0 eV and the interesting optical properties highlight them prospective materials for optoelectronic applications.

Diet-Right: A Smart Food Recommendation System

( Faisal Rehman ),( Osman Khalid ),( Nuhman Ul Haq ),( Atta Ur Rehman Khan ),( Kashif Bilal ),( Sajjad A. Madani ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.6

Inadequate and inappropriate intake of food is known to cause various health issues and diseases. Due to lack of concise information about healthy diet, people have to rely on medicines instead of taking preventive measures in food intake. Due to diversity in food components and large number of dietary sources, it is challenging to perform real-time selection of diet patterns that must fulfill one`s nutrition needs. Particularly, selection of proper diet is critical for patients suffering from various diseases. In this article, we highlight the issue of selection of proper diet that must fulfill patients` nutrition requirements. To address this issue, we present a cloud based food recommendation system, called Diet-Right, for dietary recommendations based on users` pathological reports. The model uses ant colony algorithm to generate optimal food list and recommends suitable foods according to the values of pathological reports. Diet-Right can play a vital role in controlling various diseases. The experimental results show that compared to single node execution, the convergence time of parallel execution on cloud is approximately 12 times lower. Moreover, adequate accuracy is attainable by increasing the number of ants.

Preparation of superparamagnetic maghemite (γ-Fe2O3) nanoparticles by wet chemical route and investigation of their magnetic and dielectric properties

Kashif Ali,A.K. Sarfraz,Imran M. Mirza,A. Bahadur,S. Iqbal,A. ul Haq 한국물리학회 2015 Current Applied Physics Vol.15 No.8

Maghemite (γ-Fe2O3) nanoparticles have been synthesized using a wet chemical route, optimizing the reaction time, PH value and size of the crystallite during synthesis. The Powder X-ray diffraction (XRD) measurements confirmed the presence of an impurity free maghemite phase in our sample with an average crystallite size of 16 nm as calculated from the DebyeeScherrer equation. In physical characterization, the room temperature hysteresis (M-H loop) and blocking temperature (as observed from the M-T plot) revealed that the particles are in the superparamagnetic phase at room temperature. Dielectric behaviour of γ-Fe2O3 with respect to the variation of frequency and temperature was also performed. At room temperatures, we observe a decaying behaviour of both dielectric constant (έ) and tangent looses (tanδ) at smaller frequencies while at higher frequencies both saturate to smaller constant values. In temperature dependent dielectric properties we notice that the dielectric constant (both real and imaginary parts) show an increasing trend with increasing temperatures but an overall slower enhancement at elevated frequencies. The former effect can be attributed to the possible delocalization of impurities at higher temperatures while the latter effect can be explained as an inability of the electric dipole moments to respond at higher frequencies.

Synchronous Reference Frame Theory Based Intelligent Controller for Current THD Reduction

Al-Ammar Essam A.,Ul Haq Azhar,Iqbal Ahsan,Ko Wonsuk,Jalal Marium,Anjum Muhammad Almas,Choi Hyeong-Jin,Kang Hyun-Koo 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

Concerns related to current harmonics have gained increased attention in recent years due to technological advancement in power electronics and the proliferation of non-linear loads in power distribution system. It has become challenging to limit current total harmonic distortion (THD) at consumer end mainly due to increased penetration of intermittent switching based non-linear loads. Shunt active power fi lter (SAPF) is considered a marvelous power electronics device to tackle consumer side current harmonics. This paper presents a synchronous reference frame (SRF) based improved control method for compliant working of SAPF to reduce current harmonics in the distribution network with same and diff erent THD levels in three phases. This research work investigates an eff ectual DC link voltage control technique linked with SRF based control of SAPF to eff ectively mitigate current harmonics. A fuzzy logic-based automatic switch (FLBAS) is designed according to the THD standards of IET and IEEE for real-time controlling of SRF based control of SAPF. In addition, S-plane stability analysis of the proposed control scheme is performed using the model of SAPF’s inverter. It is established that the closed-loop system is asymptotically stable with the proposed control scheme. The presented simulation results validate the eff ectiveness of the proposed control technique for SAPF robustly.

Thermal energy performance due to convection process of nanofluid in a porous medium due to split lid motion in a right triangular enclosure

Ullah M Zaka,Hussain S T,Haq Rizwan Ul,Alzahrani A Khamis,Mallawi Fouad 한국CDE학회 2022 Journal of computational design and engineering Vol.9 No.3

In the current phenomena, a study is carried out for the convection process of nanofluid within the porous media enclosed in a triangular permeable cavity. The heat generation effect within the nanofluid is developed when the two heat sources are applied through the split lids. To analyse the behaviour of nanofluids and steam lines, we have considered an elliptic (cold, adiabatic, and heated)-shaped obstacle that is placed inside the cavity. Mathematical modelling is carried out through continuity, momentum equation, and energy equations in the form of a system of non-linear partial differential equations. These equations are produced after incorporating the relations of viscosity, density, shapes of nanoparticle, and thermal conductivity for nanofluids Constraints are adjusted according to the forced convection due to the upper moving wall of the cavity. Four different cases of the upper double lid-driven wall are considered. All the emerging parameters, namely Reynolds number $( {25 \le {\rm{Re}} \le 750} ),$ heat generation $( { - {{10}^4} \le Q \le 40} ),\ $ nanoparticle volume fraction $\ ( {0 \le \phi \le 0.2} )$, and Darcy number ${10^{ - 5}} \le Da \le {10^{ - 3}}$, are analysed through variation of velocities, temperature profile, isotherms, and streamlines. Various cases at the surface of the inner elliptical obstacle provide significant contributions in the variation of heat transfer rate and velocity profiles. Nanoparticles provide a considerable increase in the heat transfer rate. The Darcy number shows the substantial variation in the formation of the isothermal region. An increase in heat generation parameter Q provides an improvement in temperature distribution inside the cavity and it also caused the formation of a single isothermal region around the heated obstacle.

Novel Nonsense Variants c.58C>T (p.Q20X) and c.256G>T (p.E85X) in the CHEK2 Gene Identified dentified in Breast Cancer Patients from Balochistan

Baloch, Abdul Hameed,Khosa, Ahmad Nawaz,Bangulzai, Nasrullah,Shuja, Jamila,Naseeb, Hafiz Khush,Jan, Mohammad,Marghazani, Illahi Bakhsh,Kakar, Masood-ul-Haq,Baloch, Dost Mohammad,Cheema, Abdul Majeed,A Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.3

Breast cancer is the most commonly occurring and leading cause of cancer deaths among women globally. Hereditary cases account 5-10% of all the cases and CHEK2 is considered as a moderate penetrance breast cancer risk gene. CHEK2 plays a crucial role in response to DNA damage to promote cell cycle arrest and repair DNA damage or induce apoptosis. Our objective in the current study was to analyze mutations in the CHEK2 gene related to breast cancer in Balochistan. A total of 271 individuals including breast cancer patients and normal subjects were enrolled. All 14 exons of CHEK2 were amplified and sequenced. The majority of the patients (>95%) had invasive ductal carcinomas (IDCs), 52.1% were diagnosed with tumor grade III and 56.1% and 27.5% were diagnosed with advance stages III and IV. Two novel nonsense variants i.e. c.58C>T (P.Q20X) and c.256G>T (p.E85X) at exon 1 and 2 in two breast cancer patients were identified in the current study. Both the variants identified were novel and have not been reported elsewhere.