| 1. |
- Ans, Muhammad, et al.
(författare)
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Designing of non-fullerene 3D star-shaped acceptors for organic solar cells
- 2019
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Ingår i: Journal of Molecular Modeling. - : Springer. - 1610-2940 .- 0948-5023. ; 25:5
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Tidskriftsartikel (refereegranskat)abstract
- The design and fabrication of solar cells have recently witnessed the exploration of non-fullerene-based acceptor molecules for higher efficiency. In this study, the optical and electronic properties of four new three-dimensional (3D) star-shaped acceptor molecules (M1, M2, M3, and M4) are evaluated for use as acceptor molecules in organic solar cells. These molecules contain a triphenylamine donor core with diketopyrrolopyrrole acceptor arms linked via a thiophene bridge unit. Molecules M1–M4 are characterized by different end-capped acceptor moieties, including 2-(5-methylene-6-oxo-5,6-dihydrocyclopenta-b-thiophen-4-ylidene)malononitrile (M1), 2-(2-methylene-3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (M2), 2-(5-methyl-2-methylene-3-oxo-2,3-dihydroinden-1-ylidene)malononitrile (M3), and 3-methyl-5-methylnene-thioxothiazolidin-4-one (M4). The properties of the newly designed molecules were compared with a well-known reference compound R, which was recently reported as an excellent acceptor molecule for organic solar cells. Molecules M1–M4 exhibit suitable frontier molecular orbital patterns for charge mobility. M2 shows maximum absorption (λmax) at 846.8 nm in dichloromethane solvent, which is ideal for the design of transparent solar cells. A strong electron withdrawing end-capped acceptor causes a red shift in absorption spectra. All molecules are excellent for hole mobility due to a lower value of λh compared to the reference R.
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| 2. |
- Javed, Iqbal, et al.
(författare)
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Quinacridone-Based Small Acceptor Molecule for Obtaining High Open Circuit Voltage in Solution Processed Organic Solar Cells
- 2015
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Ingår i: Journal of the Chemical Society of Pakistan. - : Chemical Society of Pakistan. - 0253-5106. ; 37:3, s. 418-425
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Tidskriftsartikel (refereegranskat)abstract
- Dioctylquinacridone di(cyanoimine) CN-DOQA was synthesized according to previously reported method. CN-DOQA having suitable HOMO-LUMO energy levels due to -CN groups as electron withdrawing groups was used in organic solar cells as an acceptor in a blend with poly (3-hexyl thiophene) (P3HT) as donor. The photovoltaic devices have shown reasonable high open circuit voltage (Voc) although solar cells have not been fully optimized. Photovoltaic study was supported by thermogravimetric analysis (TGA), dynamic scanning calorimetry (DSC) of CN-DOQA and morphological study of the blend films by atomic force microscopy (AFM).
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| 3. |
- Javed, Muhammad Sufyan, et al.
(författare)
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The energy crisis in Pakistan : A possible solution via biomass-based waste
- 2016
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Ingår i: Journal of Renewable and Sustainable Energy. - : American Institute of Physics (AIP). - 1941-7012. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- Developing countries like Pakistan need a continuous supply of clean and cheap energy. It is a very common fear in today's world that the fossil fuels will be depleted soon and the cost of energy is increasing day-by-day. Renewable energy sources and technologies have the potential to provide solutions to long-standing energy problems faced by developing countries. Currently, Pakistan is experiencing a critical energy crisis and renewable energy resources can be the best alternatives for quickly terminating the need for fossil fuels. The renewable energy sources such as solar energy, wind energy, and biomass energy combined with fuel cell technology can be used to overcome the energy shortage in Pakistan. Biomass is a promising renewable energy source and is gaining more interest because it produces a similar type of fuel like crude oil and natural gas. Energy from biomass only depends upon the availability of raw materials; therefore, biomass can play an important role to fulfill the energy requirements of the modern age. The use of energy has increased greatly since the last century and almost all human activities have become more dependent on energy. Biomass, being a potential and indigenous candidate, could be a good solution to meet the energy needs of Pakistan. In this review paper, the detailed current energy requirements and solutions from available energy resources and the scope, potential, and implementation of biomass conversion to energy in Pakistan are explored with a special focus on the major province of Punjab and the advantages of biomass for energy purposes.
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| 4. |
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| 5. |
- Raza, Rizwan, et al.
(författare)
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Ce-0.8(SmZr)(0.2)O-2-carbonate nanocomposite electrolyte for solid oxide fuel cell
- 2014
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 38:4, s. 524-529
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Tidskriftsartikel (refereegranskat)abstract
- A nanocomposite Zr/Sm-codoped ceria electrolyte coated with K2CO3/Na2CO3 was synthesized by a coprecipitation method. The electrochemical study of the two-phase nanocomposite electrolytes with carbonate coated on the doped ceria shows high oxygen ion mobility at low temperatures (300-600 degrees C). The interface between the two constituent phases was studied by electrochemical impedance spectroscopy. Ionic conductivities were also measured with electrochemical impedance spectroscopy. The morphology and structure of composite electrolyte were characterized using field-emission scanning electron microscopy and X-ray diffraction. The fuel cell power density is 700 mW cm(-2), and an open-circuit voltage of 1.00 V is achieved at low temperatures (400-550 degrees C). This codoped approach with a second phase provides a good indication regarding overcoming the challenges of solid oxide fuel cell technology.
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| 6. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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| 7. |
- Adnan, Muhammad, et al.
(författare)
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Fine Tuning the Optoelectronic Properties of Triphenylamine Based Donor Molecules for Organic Solar Cells
- 2017
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Ingår i: Zeitschrift fur physikalische Chemie (Munchen. 1991). - : Walter de Gruyter GmbH. - 0942-9352 .- 2196-7156. ; 231:6, s. 1127-1139
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Tidskriftsartikel (refereegranskat)abstract
- Geometrical parameters, electronic structures and photophysical properties of three new triphenylamine (TPA) and diphenylamine (DPA) based electron donor materials M1-M3 (for organic solar cells) have been investigated through density functional theory (DFT) methods at the B3LYP/6-31G(d) level of the theory. TPA and DPA are used as donor moieties due to their electron donating ability while benzothiazole, cyanide and cyanomethylacetate (CMA) moieties have been taken as acceptor moieties. The time dependent-DFT (TD-DFT) method has been employed [TD-B3LYP/6-31G (d)] for the computation of excited state properties in the gas phase and in solvent (chloroform). The polarization continuum model is applied for calculations in the solvent phase. The designed molecules exhibited broad absorption in the visible and near infra-red region of spectrum with respect to a reference molecule "R" of a similar class of compounds. Based on reorganization energies calculations, these materials could act as excellent hole transport materials.
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| 8. |
- Ahmed, A., et al.
(författare)
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Highly efficient composite electrolyte for natural gas fed fuel cell
- 2016
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 41:16, s. 6972-6979
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Tidskriftsartikel (refereegranskat)abstract
- Solid oxide fuel cells (SOFCs) have the ability to operate with different variants of hydro carbon fuel such as biogas, natural gas, methane, ethane, syngas, methanol, ethanol, hydrogen and any other hydrogen rich gas. Utilization of these fuels in SOFC, especially the natural gas, would significantly reduce operating cost and would enhance the viability for commercialization of FC technology. In this paper, the performance of two indigenously manufactured nanocomposite electrolytes; barium and samarium doped ceria (BSDC-carbonate); and lanthanum and samarium doped ceria (co-precipitation method LSDC-carbonate) using natural gas as fuel is discussed. The nanocomposite electrolytes were synthesized using co-precipitation and wet chemical methods (here after referred to as nano electrolytes). The structure and morphology of the nano electrolytes were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The fuel cell performance (OCV) was tested at temperature (300-600 °C). The ionic conductivity of the nano electrolytes were measured by two probe DC method. The detailed composition analysis of nano electrolytes was performed with the help of Raman Spectroscopy. Electrochemical study has shown an ionic conductivity of 0.16 Scm-1 at 600 °C for BSDC-carbonate in hydrogen atmosphere, which is higher than conventional electrolytes SDC and GDC under same conditions. In this article reasonably good ionic conductivity of BSDC-carbonate, at 600 °C, has also been achieved in air atmosphere which is comparatively greater than the conventional SDC and GDC electrolytes.
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| 9. |
- Ali, Qasim, et al.
(författare)
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Drought tolerance potential of Vigna mungo L. lines as deciphered by modulated growth, antioxidant defense, and nutrient acquisition patterns
- 2016
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Ingår i: Revista Brasileira de Botânica. - : Springer. - 0100-8404 .- 1806-9959. ; 39:3, s. 801-812
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Tidskriftsartikel (refereegranskat)abstract
- Water shortage is one of the major environmental constraints that hamper the crop productivity worldwide. The present study was aimed to examine the drought tolerance potential of seven cultivars/lines of Vigna mungo L. depending upon their germination behavior, seedling growth, antioxidative defense mechanism, and nutrient acquisition. An experiment was conducted in the growth chamber using petri-plates and laid out in a completely randomized design (CRD). Hoagland's nutrient solution supplemented with 12 % PEG-8000 (drought treatment) or without PEG-800 (control) was used. Drought stress significantly altered the germination attributes as well as biomass production of all the studied cultivars/lines. Least adversative effects of drought stress were recorded in lines M-01001-1 and M-6036-21, respectively. The studied cultivars/lines exhibited differential response for various biochemical attributes under drought stress. The maximum increase in MDA and SOD activities and protein content was recorded in line M-603621, while the maximum AsA was recorded in line M-01001-1. Drought stress resulted in a significant reduction of plant N, P, K, Ca, and Mg contents, while the plant iron (Fe) contents remained unaffected. Results revealed that cultivars/lines M-01001-1 and M-6036-21 exhibited enhanced performance in terms of nutrient acquisition when stressed by drought. Based upon seed germination behavior, plant biomass production, biochemical attributes and mineral elements, the cultivars/lines M-01001-1 and M-6036-21 were identified as drought tolerant, while M-97 and Arroj-II were identified as drought sensitive.
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| 10. |
- Ans, Muhammad, et al.
(författare)
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Designing Three‐dimensional (3D) Non‐Fullerene Small Molecule Acceptors with Efficient Photovoltaic Parameters
- 2018
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Ingår i: ChemistrySelect. - : WILEY-VCH VERLAG GMBH. - 2365-6549. ; 3:45, s. 12797-12804
-
Tidskriftsartikel (refereegranskat)abstract
- Three dimensional (3D) acceptor‐donor‐acceptor (A−D‐A) type small molecules (M1, M2, M3 and M4) are theoretically investigated for optoelectronic properties. The designed molecules contain spirobifluorene as core unit linked with end capped acceptors through four four thieno‐[3,2‐b]Thiophene (TT) units. The end capped acceptors are (3‐methyl‐2‐thioxothiazolidin‐4‐one) (M1), 2‐(2‐ethylidene‐5,6‐difluoro‐3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (M2), 2‐(3‐ethyl‐4‐oxothiazolidin‐2‐ylidine)malononitrile (M3) and 2‐(2‐ethylidene‐5,6‐dicyano‐3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile (M4). The photovoltaic parameters of the designed molecules are compared with the recently reported reference compound R. Among all designed molecules, M4 is a low energy gap material (2.28 eV), broad absorption which is attributed to excellent communication between strong electron withdrawing end capped acceptors through extended conjugation. All newly designed molecules have lower binding energy as compared to reference molecule R which results in higher exciton dissociation in excited state. The reorganization energy calculations indicate good charge transfer ability of the designed molecules. M4 shows the lowest λe (0.0022) value with respect to the reference molecule R (0.034) which signifies its enhanced electronic transport behavior. The calculated open circuit voltages (Voc) ranges from 1.97 to 2.36 eV, 2.11 to 2.49 eV and 1.9 eV to 2.28 eV with respect to three different well known donor materials PTB7‐Th, PBDB−T and P3HT, respectively.
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| 11. |
- Ans, Muhammad, et al.
(författare)
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Opto-electronic properties of non-fullerene fused-undecacyclic electron acceptors for organic solar cells
- 2019
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Ingår i: Computational materials science. - : Elsevier. - 0927-0256 .- 1879-0801. ; 159, s. 150-159
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Tidskriftsartikel (refereegranskat)abstract
- Due to limitations of fullerene based acceptor molecules for solar cell applications, research is recently diverted to explore non-fullerene acceptor molecules. In this regard, four new A-D-A type fused ring electron acceptor molecules (M1, M2, M3 and M4) are evaluated for their opto-electronic properties for transparent organic solar cells. These molecules contain strong electron donor undecacyclic linked with four different acceptor moieties, 2-(3-ethly-5-methylene-4-oxothiazolidin-2-yluidene)malononitrile (M1), 2-(5,6-dicyano-2-methylene-3-oxo -2,3-dihydroindene-1-ylidene)malononitrile (M2), 2-(5-methylene-6-oxo-tetrahydro-1H-cyclopenta-thiophene-4(5H)-ylidene)malononitrile (M3), and 3-ethyl-5-methylene-2-thioxothiazolidin-4-one (M4). The electronic and optical properties of these molecules are compared with the reference molecule R, which is recently reported as excellent non-fullerene based acceptor molecule. Among all molecules, M2 exhibits the maximum red shift where absorption appears 893.5 nm with B3LYP/6-31 + + G(d,p) level of theory due to highly extended conjugation between electron withdrawing end-capped acceptor moieties. The calculated Open circuit voltage (V-oc) of reference molecule R is 1.78 eV with donor polymer PTB7-Th while molecule M2 exhibits the V-oc value of 1.86 eV.
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| 12. |
- Ans, Muhammad, et al.
(författare)
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Spirobifluorene based small molecules as an alternative to traditional fullerene acceptors for organic solar cells
- 2019
-
Ingår i: Materials Science in Semiconductor Processing. - : Elsevier. - 1369-8001 .- 1873-4081. ; 94, s. 97-106
-
Tidskriftsartikel (refereegranskat)abstract
- Four new three-dimensional (3D) acceptor-acceptor-donor (A-A-D) type of small molecule acceptors (Ml, M2, M3 and M4) were designed for better optoelectronic properties in organic solar cells. These molecules contain spirobifluorene as a 3D core unit, flanked with 2,1,3- benzothiadiazole (BT) units linked with the end-capped acceptor groups 2-(4-oxo-4,5-dihydrocyclopenta-b-thiophene-6-ylidene)malononitrile (M1), 2-(3-oxo-2,3-dihydro-1H-indene-1-indene-1-ylidene)malononitrile (M2), 2-(5,6-difluoro-3-oxo-2,3-dihydroindene-1-ylidene) malononitrile (M3) and 2-(5,6-dimethyl-3-oxo-2,3-dihydroindene-1-ylidene)malononitrile (M4). The optoelectronic properties of M1 -M4 were compared with the well-known reference molecule R, which has the same central BT-spirobifluorene-BT structure as Ml-M4 but is end-capped with the 2-(2-dicyanomethylene)-3-ethyl-4-oxo-thiazolidin-5-ylidenemethyl group. Among these molecules, M3 has the most appropriate frontier molecular orbital diagram for optoelectronic properties as deduced from MPW1PW91 calculations and also shows the maximum absorption peak at longest wavelength (569 nm) by TD-MPW1PW91 calculations with a polarizable continuum model for chloroform solution. These properties are due to the strong electron-withdrawing end-capped acceptor group which causes a red shift in the absorption spectrum. Computed reorganization energies indicate that the electron mobilities for M1-M4 are higher compared to that of reference R.
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| 13. |
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Benchmark study of bond dissociation energy of Si-X (X=F, Cl, Br, N, O, H and C) bond using density functional theory (DFT)
- 2017
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Ingår i: Journal of Molecular Structure. - : Elsevier. - 0022-2860 .- 1872-8014. ; 1143, s. 8-19
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Tidskriftsartikel (refereegranskat)abstract
- A benchmark study of Bond Dissociation Energies (BDEs) of various chemical bonds is carried out by Density Functional theory (DFT) method. The aim of the present research study was to find out the best suited functional and basis set to calculate BDEs of selected bonds of silicon with halogens (F, Cl, Br), N, H, C and O. Six different functionals (CAM/B3LYP, B3LYP, B3PW91, PBEPBE, TPSSTPSS) were applied on 36 molecules of different nature. Furthermore, six different basis sets 3-21G, aug-cc-pVTZ, 6-31G, aug-cc-pVDZ, DGDZVP and DGDZVP2 were also applied on these molecules with the best suited functional CAM/B3LYP. After rigorous effort it can be safely said that the best basis set for calculating BDEs for Si H, Si-C, Si-N bonds using CAM-B3LYP functional is 3-21G and for Si-halogens,aug-cc-pVTZ was found to be best basis set.
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| 14. |
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| 15. |
- Huang, Bingzhang, et al.
(författare)
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Evolutionary Algorithms for Strength Prediction of Geopolymer Concrete
- 2024
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Ingår i: Buildings. - : MDPI. - 2075-5309. ; 14:5
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Tidskriftsartikel (refereegranskat)abstract
- Geopolymer concrete (GPC) serves as a sustainable substitute for conventional concrete by employing alternative cementitious materials such as fly ash (FA) instead of ordinary Portland cement (OPC), contributing to environmental and durability benefits. To increase the rate of utilization of FA in the construction industry, distinctive characteristics of two machine learning (ML) methods, namely, gene expression programming (GEP) and multi-expression programming (MEP), were utilized in this study to propose precise prediction models for the compressive strength and split tensile strength of GPC comprising FA as a binder. A comprehensive database was collated, which comprised 301 compressive strength and 96 split tensile strength results. Seven distinct input variables were employed for the modeling purpose, i.e., FA, sodium hydroxide, sodium silicate, water, superplasticizer, and fine and coarse aggregates contents. The performance of the developed models was assessed via numerous statistical metrics and absolute error plots. In addition, a parametric analysis of the finalized models was performed to validate the prediction ability and accuracy of the finalized models. The GEP-based prediction models exhibited better performance, accuracy, and generalization capability compared with the MEP-based models in this study. The GEP-based models demonstrated higher correlation coefficients (R) for predicting the compressive and split tensile strengths, with the values of 0.89 and 0.87, respectively, compared with the MEP-based models, which yielded the R values of 0.76 and 0.73, respectively. The mean absolute errors for the GEP- and MEP-based models for predicting the compressive strength were 5.09 MPa and 6.78 MPa, respectively, while those for the split tensile strengths were 0.42 MPa and 0.51 MPa, respectively. The finalized models offered simple mathematical formulations using the GEP and Python code-based formulations from MEP for predicting the compressive and tensile strengths of GPC. The developed models indicated practical application potential in optimizing geopolymer mix designs. This research work contributes to the ongoing efforts in advancing ML applications in the construction industry, highlighting the importance of sustainable materials for the future.
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| 16. |
- Iqbal, Javed, et al.
(författare)
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A Novel Single-Fed Dual-Band Dual-Circularly Polarized Dielectric Resonator Antenna for 5G Sub-6GHz Applications
- 2022
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- In this research article, a single-fed dual-band circular polarized (CP) dielectric resonator antenna (DRA) for dual-function communication, such as GPS and WLAN, was made. Initially, the proposed design process was initiated by designing a linearly polarized singly fed-DRA. To attain CP fields, the cross-shape conformal metal strip was optimized to excite the fundamental and the high-order mode in the two frequency bands. The metallic strip (parasitic) was utilized on top of the rectangular DRA to improve and widen the impedance and axial ratio (AR) bandwidth. This step led to a 2.73% improvement on the lower band and an impact of 6.5% on the upper band while on the other side a significant improvement was witnessed in the AR bandwidth in both frequency bands. A prototype was designed and fabricated in order to validate its operations. The measurement outcomes of the proposed antennas authenticated wideband impedance bandwidths of 6.4% and 25.26%, and 3-dB axial ratios (AR) of 21.26% and 27.82% respectively. The prototype is a decent candidate for a global positioning system (GPS) and wireless local area network (WLAN).
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| 17. |
- Iqbal, Javed, et al.
(författare)
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An arylene-vinylene based donor-acceptor-donor small molecule for the donor compound in high-voltage organic solar cells
- 2016
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 155, s. 348-355
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Tidskriftsartikel (refereegranskat)abstract
- A donor-acceptor-donor (D-A-D) molecule has been designed and synthesized for use as the electron donating material in solution-processed small-molecule organic solar cells (OSCs). The D-A-D molecule comprises a central electron-accepting (2Z,2'Z)-2,2'-(2,5-bis(octyloxy)-1,4-phenylene)bis(3-(thiophen-2-yl)acry lonitrile) (ZOPTAN) core, which is chemically connected to two peripheral and electron-donating triphenylamine (TPA) units. The ZOPTAN-TPA molecule features a low HOMO level of -5.2 eV and an optical energy gap of 2.1 eV. Champion OSCs based on a solution-processed and non-annealed active material blend of [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) and ZOPTAN-TPA in a mass ratio of 2:1 exhibits a power conversion efficiency of 1.9% and a high open-circuit voltage of 1.0 V.
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| 18. |
- Irfan, Muhammad, et al.
(författare)
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Benchmark study of UV/Visible spectra of coumarin derivatives by computational approach
- 2017
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Ingår i: Journal of Molecular Structure. - : Elsevier BV. - 0022-2860 .- 1872-8014. ; 1130, s. 603-616
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Tidskriftsartikel (refereegranskat)abstract
- A benchmark study of UV/Visible spectra of Simple coumarins and Furanocoumarins derivatives was conducted by employing the Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) approaches. In this study the geometries of ground and excited states, excitation energy and absorption spectra were estimated by using the DFT functional CAM-B3LYP, WB97XD, HSEH1PBE, MPW1PW91 and TD-B3LYP with 6-31 + G (d,p) basis set. CAM-B3LYP functional was found to have close agreement with the experimental values of Furranocoumarin class of coumarins while MPW1PW91 gave close results for simple coumarins. This study provided an insight about the electronic characteristics of the selected compounds and provided an effective tool for developing and designing the better UV absorber compounds.
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| 19. |
- Irfan, Muhammad, et al.
(författare)
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Design of donor-acceptor-donor (D-A-D) type small molecule donor materials with efficient photovoltaic parameters
- 2017
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Ingår i: International Journal of Quantum Chemistry. - : WILEY. - 0020-7608 .- 1097-461X. ; 117:10
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Tidskriftsartikel (refereegranskat)abstract
- Four Donor-Acceptor-Donor (D-A-D) type of donor molecules (M1-M4) with triphenylamine (TPA) as donor moiety, thiophene as bridge, and thiazolothiazole as acceptor unit were designed and its photovoltaic parameters were equated with reference molecule R. DFT functional CAM-B3LYP/6-31G (d,p) was found best for geometry optimization and TD-CAM-B3LYP/6-31G (d,p) was found suitable for excited state calculations. Among designed donor molecules, M4 manifests suitable lowest band gap of 4.73 eV, frontier molecular orbital energy levels as well as distinctive broad absorption of 455.3 nm due to the stronger electron withdrawing group. The electron-withdrawing substituents contribute to red shifts of absorption spectra and better stabilities for designed molecules. The theoretically determined reorganization energies of designed donor molecules suggested excellent charge mobility property. The lower (e) values in comparison with (h) illustrated that these four donor materials would be ideal for electron transfer and M4 would be best amongst the investigated molecules with lowest (e) of 0.0177. Furthermore, the calculated Voc of M4 is 2.04 V with respect to PC60BM (phenyl-C61-butyric acid methyl ester). This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.
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| 20. |
- Irfan, Muhammad, et al.
(författare)
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Tuning the Optoelectronic Properties of Naphtho-Dithiophene-Based A-D-A Type Small Donor Molecules for Bulk Hetero-Junction Organic Solar Cells
- 2018
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Ingår i: ChemistrySelect. - : John Wiley & Sons. - 2365-6549. ; 3:8, s. 2352-2358
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Tidskriftsartikel (refereegranskat)abstract
- Four acceptor-donor-acceptor (A-D-A) type small molecules using naphtho-dithiophene as central building block, trithiophene as -bridges, malononitrile and 2-Thioxo-thiazolidin-4-one as end acceptor groups were designed by using density functional theory (DFT) and investigated as donor materials for organic solar cells (OSCs). The effects of end acceptor groups on absorption, charge transport, morphology, energy level and photovoltaic properties of the molecules were investigated and compared with reference molecule (R1= NDTP-CNCOO). These designed molecules showed relatively low HOMO levels of -5.46 to -5.56eV, strong absorption between 440-650nm by using chloroform as solvent. The designed donor molecules have an excellent electron mobility from 0.0161 to 0.0201V, hole mobility from 0.0275 to 0.0307V and open circuit voltage (Voc) from 1.76 to 1.86V. This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.
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| 21. |
- Jabeen, Sobia, et al.
(författare)
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Tuning Optoelectronic Properties of Dithienopyrrole Donor Molecules for Organic Solar Cells
- 2019
-
Ingår i: Russian Journal of Physical Chemistry. - : Maik Nauka/Interperiodica. - 0036-0244 .- 1531-863X. ; 93:11, s. 2233-2243
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical analysis of physical properties of organic solar cells (OSCs) are important in order to reveal the correlation between power conversion efficiencies (PCE), structure and properties. Five new A-D-A type small molecules M-1, M-2, M-3, M-4, and M-5 were designed by using dithienopyrrole (DTP) as electron rich donor unit with different types of pi-spacers and end capped acceptor units. Functional MPW1PW91/6-31G(d,p) level of theory was used to optimize the geometry of all molecules. For excited state calculation TD-MPW1PW91/6-31G(d,p) level of theory was used. The geometries, electronic structures, dipole moment, open circuit voltage, reorganization energies and charge transport properties of designed molecules M-5) have been scrutinized comparing with the reported compound R. The results revealed that the HOMO energy levels of molecules M-1, M-2, M-3, and M-5 were lower while M-4 was of high energy level thus facilitate the donation of electron as compared to references molecule R. While LUMO energy level of all the molecules were slightly high energy due electron withdrawing effects of spacer and acceptor moiety. Highest energy gap of HOMO-LUMO was observed in M-1 which was 2.48 eV and M-3 showed low energy gap (2.11 eV) as compared to other designed molecules. All molecules showed low values for lambda(e), so they have high rate of electron transfer as compared to R. All designed molecules exhibited higher value of dipole moment as compared to reference molecule R except M-1. Higher value of dipole moment of donor molecules contrary to reference means good solubility towards organic solvents which is beneficial for further solar cell device fabrication. All designed molecules show higher V-oc values except M-4 which has comparable V-oc with respect to reference molecule R. In short, choice of appropriate electron withdrawing and donating groups is very important for improving power conversion efficiencies of OSCs.
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| 22. |
- Javed, Iqbal, et al.
(författare)
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Photophysical and electrochemical properties and temperature dependent geometrical isomerism in alkyl quinacridonediimines
- 2014
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Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry. - 1144-0546 .- 1369-9261. ; 38:2, s. 752-761
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Tidskriftsartikel (refereegranskat)abstract
- Quinacridone diimines 1-10 were synthesized by the condensation of anilines with alkyl substituted quinacridones (QA). Photophysical and electrochemical properties of the compounds were investigated. Unconventional behavior of absorption spectra suggested a decrease in pi(-)conjugation within the QA skeleton as well as lack of extended pi(-)conjugation between the QA skeleton and the N-phenyl rings. A computational study of compounds 1-10, a variable temperature H-1 NMR study of compounds 2, 7 and 10 (for instance), and single crystal X-ray analysis of 2, 3, 6, 7, 8 and 10 indicated that the anomalous behavior is due to the buckled, non-planar structure of the quinacridones. Moreover the molecules existed in two interconvertible geometric isomeric forms at different temperatures. Molecular orbital calculations were performed at B3LYP/6-31+G(d), B3PW91/6-31G(d) and PBEPBE/6-31G(d) levels of theory at B3PW91/6-31G(d) optimized structures for both isomers of all compounds (1-10); the results obtained are in close agreement with the experimentally determined values.
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| 23. |
- Khan, Muhammad Ahsan Iqbal, et al.
(författare)
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An Experimental and Comparative Performance Evaluation of a Hybrid Photovoltaic-Thermoelectric System
- 2021
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Ingår i: Frontiers in Energy Research. - : FRONTIERS MEDIA SA. - 2296-598X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The majority of incident solar irradiance causes thermalization in photovoltaic (PV) cells, attenuating their efficiency. In order to use solar energy on a large scale and reduce carbon emissions, their efficiency must be enhanced. Effective thermal management can be utilized to generate additional electrical power while simultaneously improving photovoltaic efficiency. In this work, an experimental model of a hybrid photovoltaic-thermoelectric generation (PV-TEG) system is developed. Ten bismuth telluride-based thermoelectric modules are attached to the rear side of a 10 W polycrystalline silicon-based photovoltaic module in order to recover and transform waste thermal energy to usable electrical energy, ultimately cooling the PV cells. The experiment was then carried out for 10 days in Lahore, Pakistan, on both a simple PV module and a hybrid PV-TEG system. The findings revealed that a hybrid system has boosted PV module output power and conversion efficiency. The operating temperature of the PV module in the hybrid system is reduced by 5.5%, from 55 degrees C to 52 degrees C. Due to a drop in temperature and the addition of some recovered energy by thermoelectric modules, the total output power and conversion efficiency of the system increased. The hybrid system's cumulative output power increased by 19% from 8.78 to 10.84 W, compared to the simple PV system. Also, the efficiency of the hybrid PV-TEG system increased from 11.6 to 14%, which is an increase of 17% overall. The results of this research could provide consideration for designing commercial hybrid PV-TEG systems.
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| 24. |
- Khan, Muhammad Abbas, et al.
(författare)
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mmWave Four-Element MIMO Antenna for Future 5G Systems
- 2022
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Ingår i: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:9, s. 4280-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an S-shape four-port Multiple Input Multiple Output (MIMO) wideband mmWave antenna with bandwidth of 25 GHz to 39 GHz. The antenna is designed on 0.254 mm ultra-thin RO5880 with permittivity of 2.3. The dimensions of proposed S-shape antenna are 10 x 12 mm for single element and 24 x 24 mm for four-port MIMO configuration. A decoupling network is introduced to further compress mutual coupling among MIMO elements. The peak gain achieved is 7.1 dBi and MIMO assembly delivers diversity scheme. The proposed MIMO antenna is fabricated, and simulated results are found to be in excellent agreement with simulations. Through the results obtained, the proposed MIMO antenna system can be considered as a potential candidate for future mmWave devices.
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| 25. |
- Manzoor, Farah, et al.
(författare)
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Theoretical Calculations of the Optical and Electronic Properties of Dithienosilole- and Dithiophene-Based Donor Materials for Organic Solar Cells
- 2018
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Ingår i: ChemistrySelect. - : Wiley - V C H Verlag GmbH. - 2365-6549. ; 3:5, s. 1593-1601
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Tidskriftsartikel (refereegranskat)abstract
- Six Acceptor-Donor-Acceptor (A-D-A) types molecules with dimethyl dithieno[3, 2-b:2',3'-d]silole) -2,6-diyl (DTS) (M-1-M-3) and dimethyl cyclopenta [2, 1-b;3,4-b]-dithiophene (CPDT) (M-4-M-6) core flanged by different acceptor units through methylthiophene bridge are evaluated as donor materials for photovoltaic applications. The photovoltaic properties of M-1-M-3 and M-4-M-6 are compared with standard RaRc and R-b,R-d respectively. Geometry optimization was performed with CAM-B3LYP/6-31G (d) level of theory. TD-CAM-B3LYP has been employed for the estimation of excited state properties of the molecules. M-1, M-2, M-3 and M-4, M-5, M-6 symbolized suitable frontier molecular orbital's (FMO's) energy levels with broad absorption spectra. The electron withdrawing substituents impart red shift in absorption spectra along with good consistancy of designed donor molecules. Reorganization energies of donor molecules (M-1-M-6) showed ideal properties of charge mobility. M-1 and M-4 illustrated lowest le values as compared to lambda(h), thus dictated that designed donor molecules are of good choice for their electron donating ability. Furthermore, M-2 and M-6 demonstrated shortest Eg of 3.7 and 3.72 eV among HOMO and LUMO energy levels.
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| 26. |
- Sahar, Anum, et al.
(författare)
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UV absorbers for cellulosic apparels : A computational and experimental study
- 2018
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Ingår i: Spectrochimica Acta Part A - Molecular and Biomolecular Spectroscopy. - : Elsevier. - 1386-1425 .- 1873-3557. ; 188, s. 355-361
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Tidskriftsartikel (refereegranskat)abstract
- Two triazine based Ultra Violet (UV) absorbers Sulfuric acid mono-(2-{4-[4-chloro-6-(4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino-phenylamino)-[1,3,5]triazin-2-ylamino]-benzenesulfonyl}-ethyl) ester (1a) and 4-{4-chloro-6-[4-(2-sulfooxy-ethanesulfonyl)-phenylamino]-[1,3,5] triazin-2-ylamino}-2-[4-chloro-6-(2-sulfooxy-ethanesulfonyl)-[1,3,5]triazin-2-ylamino]-benzenesulfonic acid (2a) with different substituents were designed computationally. The influence of different substituents on the electrochemical properties and UV spectra of the absorbers was investigated. The presence of electron deficient unit in 1a to the molecular core significantly reduces the LUMO levels and energy gap. The designed absorbers were synthesized via condensation reaction and characterized by UV–Vis, FT-IR, MS studies. The performance of synthesized compounds as UV absorbers and their fastness properties were assessed by finishing the cotton fabric through exhaust method at different concentration and results appeared in good range.
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| 27. |
- Shahzadi, Iram, et al.
(författare)
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Estimation of optical rotation of gamma-alkylidenebutenolide, cyclopropylamine, cyclopropyl-methanol and cyclopropenone based compounds by a Density Functional Theory (DFT) approach
- 2017
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Ingår i: Chirality. - : Wiley Periodicals. - 0899-0042 .- 1520-636X. ; 29:10, s. 634-647
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Tidskriftsartikel (refereegranskat)abstract
- Computing the optical rotation of organic molecules can be a real challenge, and various theoretical approaches have been developed in this regard. A benchmark study of optical rotation of various classes of compounds was carried out by Density Functional Theory (DFT) methods. The aim of the present research study was to find out the best-suited functional and basis set to estimate the optical rotations of selected compounds with respect to experimental literature values. Six DFT functional LSDA, BVP86, CAM-B3LYP, B3PW91, and PBE were applied on 22 different compounds. Furthermore, six different basis sets, i.e., 3-21G, 6-31G, aug-cc-pVDZ, aug-cc-pVTZ, DGDZVP, and DGDZVP2 were also applied with the best-suited functional B3LYP. After rigorous effort, it can be safely said that the best combination of functional and basis set is B3LYP/aug-cc-pVTZ for the estimation of optical rotation for selected compounds.
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| 28. |
- Solmi, Marco, et al.
(författare)
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Physical and mental health impact of COVID-19 on children, adolescents, and their families :
- 2022
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Ingår i: Journal of Affective Disorders. - : Elsevier. - 0165-0327 .- 1573-2517. ; 299, s. 367-376
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Tidskriftsartikel (refereegranskat)abstract
- Background: The COVID-19 pandemic has altered daily routines and family functioning, led to closing schools, and dramatically limited social interactions worldwide. Measuring its impact on mental health of vulnerable children and adolescents is crucial. Methods: The Collaborative Outcomes study on Health and Functioning during Infection Times (COH-FIT - www. coh-fit.com) is an on-line anonymous survey, available in 30 languages, involving >230 investigators from 49 countries supported by national/international professional associations. COH-FIT has thee waves (until the pandemic is declared over by the WHO, and 6-18 months plus 24-36 months after its end). In addition to adults, COH-FIT also includes adolescents (age 14-17 years), and children (age 6-13 years), recruited via nonprobability/snowball and representative sampling and assessed via self-rating and parental rating. Nonmodifiable/modifiable risk factors/treatment targets to inform prevention/intervention programs to promote health and prevent mental and physical illness in children and adolescents will be generated by COH-FIT. Co primary outcomes are changes in well-being (WHO-5) and a composite psychopathology P-Score. Multiple behavioral, family, coping strategy and service utilization factors are also assessed, including functioning and quality of life. Results: Up to June 2021, over 13,000 children and adolescents from 59 countries have participated in the COHFIT project, with representative samples from eleven countries. Limitations: Cross-sectional and anonymous design. Conclusions: Evidence generated by COH-FIT will provide an international estimate of the COVID-19 effect on childrens, adolescents and families, mental and physical health, well-being, functioning and quality of life, informing the formulation of present and future evidence-based interventions and policies to minimize adverse effects of the present and future pandemics on youth.
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| 29. |
- Solmi, Marco, et al.
(författare)
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The collaborative outcomes study on health and functioning during infection times in adults (COH-FIT-Adults) : Design and methods of an international online survey targeting physical and mental health effects of the COVID-19 pandemic
- 2022
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Ingår i: Journal of Affective Disorders. - : Elsevier. - 0165-0327 .- 1573-2517. ; 299, s. 393-407
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Tidskriftsartikel (refereegranskat)abstract
- Background: . High-quality comprehensive data on short-/long-term physical/mental health effects of the COVID-19 pandemic are needed. Methods: . The Collaborative Outcomes study on Health and Functioning during Infection Times (COH-FIT) is an international, multi-language (n=30) project involving >230 investigators from 49 countries/territories/regions, endorsed by national/international professional associations. COH-FIT is a multi-wave, on-line anonymous, cross-sectional survey [wave 1: 04/2020 until the end of the pandemic, 12 months waves 2/3 starting 6/24 months threreafter] for adults, adolescents (14-17), and children (6-13), utilizing non-probability/snowball and representative sampling. COH-FIT aims to identify non-modifiable/modifiable risk factors/treatment targets to inform prevention/intervention programs to improve social/health outcomes in the general population/vulnerable subgrous during/after COVID-19. In adults, co-primary outcomes are change from pre-COVID-19 to intra-COVID-19 in well-being (WHO-5) and a composite psychopathology P-Score. Key secondary outcomes are a P-extended score, global mental and physical health. Secondary outcomes include health-service utilization/ functioning, treatment adherence, functioning, symptoms/behaviors/emotions, substance use, violence, among others. Results: . Starting 04/26/2020, up to 14/07/2021 >151,000 people from 155 countries/territories/regions and six continents have participated. Representative samples of >= 1,000 adults have been collected in 15 countries. Overall, 43.0% had prior physical disorders, 16.3% had prior mental disorders, 26.5% were health care workers, 8.2% were aged >= 65 years, 19.3% were exposed to someone infected with COVID-19, 76.1% had been in quarantine, and 2.1% had been COVID 19-positive. Limitations: . Cross-sectional survey, preponderance of non-representative participants. Conclusions: . Results from COH-FIT will comprehensively quantify the impact of COVID-19, seeking to identify high-risk groups in need for acute and long-term intervention, and inform evidence-based health policies/strategies during this/future pandemics.
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| 30. |
- Solmi, Marco, et al.
(författare)
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Validation of the Collaborative Outcomes study on Health and Functioning during Infection Times (COH-FIT) questionnaire for adults
- 2023
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Ingår i: Journal of Affective Disorders. - : ELSEVIER. - 0165-0327 .- 1573-2517. ; 326, s. 249-261
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Collaborative Outcome study on Health and Functioning during Infection Times (COH-FIT; www.coh-fit.com) is an anonymous and global online survey measuring health and functioning during the COVID-19 pandemic. The aim of this study was to test concurrently the validity of COH-FIT items and the in-ternal validity of the co-primary outcome, a composite psychopathology "P-score". Methods: The COH-FIT survey has been translated into 30 languages (two blind forward-translations, consensus, one independent English back-translation, final harmonization). To measure mental health, 1-4 items ("COH-FIT items") were extracted from validated questionnaires (e.g. Patient Health Questionnaire 9). COH-FIT items measured anxiety, depressive, post-traumatic, obsessive-compulsive, bipolar and psychotic symptoms, as well as stress, sleep and concentration. COH-FIT Items which correlated r >= 0.5 with validated companion question-naires, were initially retained. A P-score factor structure was then identified from these items using exploratory factor analysis (EFA) and confirmatory factor analyses (CFA) on data split into training and validation sets. Consistency of results across languages, gender and age was assessed. Results: From >150,000 adult responses by May 6th, 2022, a subset of 22,456 completed both COH-FIT items and validated questionnaires. Concurrent validity was consistently demonstrated across different languages for COH-FIT items. CFA confirmed EFA results of five first-order factors (anxiety, depression, post-traumatic, psychotic, psychophysiologic symptoms) and revealed a single second-order factor P-score, with high internal reliability (omega = 0.95). Factor structure was consistent across age and sex. Conclusions: COH-FIT is a valid instrument to globally measure mental health during infection times. The P-score is a valid measure of multidimensional mental health.
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| 31. |
- Zahid, Nida, et al.
(författare)
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Factors associated with changes in the quality of life and family functioning scores of primary caregivers of children and young people with primary brain tumors in Karachi, Pakistan : a prospective cohort study
- 2024
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Ingår i: BMC Pediatrics. - : BioMed Central (BMC). - 1471-2431. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThere are limited data available, particularly in low- and middle-income countries (LMICs), on the long-term quality of life (QoL) and family functioning of primary caregivers of children and young people (CYPs) affected by primary brain tumors (PBTs). This study aimed to assess the factors associated with the mean change in QoL and family functioning scores of primary caregivers of CYP patients with PBTs 12 months posttreatment.MethodsThis prospective cohort study enrolled CYPs aged 5–21 years with newly diagnosed PBTs and their primary caregivers. The study was carried out between November 2020 and July 2023. The primary caregivers of CYPs were recruited from two major tertiary care centers in Karachi, Pakistan. The primary caregivers QoL were assessed by the Pediatric Quality of Life Inventory (PedsQL) Family Impact Module. The assessment was undertaken by a psychologist at the time of diagnosis and 12 months posttreatment. The data were analyzed with STATA version 12.ResultsForty-eight CYPs with newly diagnosed PBTs and their primary caregivers (46 mothers and 2 fathers) were enrolled. At 12 months posttreatment, 25 (52%) CYPs and their primary caregivers (mothers) were reassessed, and 23 (48%) were lost to follow-up. On multivariable analysis, a significant decrease in mothers’ mean 12-month posttreatment QoL and family functioning scores was associated with CYP having posttreatment seizures (beta= -10.2; 95% CI: -18.4 to -2.0) and with the financial burden associated with the CYP’s illness (beta= -0.3; 95% CI: -0.4 to -0.1). However, in those cases where CYP had higher posttreatment quality of life scores (beta = 0.4; 95% CI = 0.1, 0.6) and posttreatment higher verbal intelligence scores (beta = 0.1; 95% CI = 0.01, 0.3), the mothers’ QoL and family functioning scores were significantly greater.ConclusionWe found a significant decrease in QoL of mothers who had a high financial burden and whose CYP had posttreatment seizures. However, those whose CYPs had higher posttreatment verbal intelligence scores and quality of life scores had significantly greater QoL scores. Identification of the factors that influence primary caregivers QoL has the potential to aid in the development of targeted strategies to alleviate stressors and improve the overall quality of life for primary caregivers and their children who are at high risk.
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| 32. |
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| 33. |
- Zahid, Nida, et al.
(författare)
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Predictors of neurocognition outcomes in children and young people with primary brain tumor presenting to tertiary care hospitals of Karachi, Pakistan : a prospective cohort study
- 2024
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Ingår i: Child's Nervous System. - : Springer. - 0256-7040 .- 1433-0350.
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Tidskriftsartikel (refereegranskat)abstract
- IntroductionPrimary brain tumors are a common cause of morbidity and mortality in children and young people (CYP) globally. Impaired neurocognitive function is a potential severe consequence in primary brain tumor (PBT) survivors. There are no in-depth studies from low- and middle-income countries (LMICs) to inform management and follow-up. The research questions of this study were as follows: Are the sociodemographic factors (lower age of CYP, female gender, low socioeconomic status, low parental education), disease-related factors (high grade of tumor, presence of seizures, presence of hydrocephalous), and treatment-related factors (adjuvant therapy, no surgical intervention, post-treatment seizures, placement of shunts) associated with decline in neurcognition outcomes 12 months post-treatment in CYP with PBTs?MethodsA prospective cohort study was conducted from November 2020 to July 2023 at the Aga Khan University Hospital and Jinnah Postgraduate Medical Centre, tertiary care hospitals in Karachi, Pakistan. All CYP aged 5 to 21 years with a newly diagnosed PBTs were eligible. The neurocognition assessment was undertaken by a psychologist at two points, i.e., pre-treatment and at 12 months post-treatment using validated tools. The verbal intelligence was assessed by Slosson Intelligence tool, revised 3rd edition (SIT-R3), perceptual reasoning by Raven’s Progressive Matrices (RPM), and the Processing Speed Index by Wechsler Intelligence Scale (WISC V) and Wechsler Adult Intelligence Scale (WAIS-IV). The data were analyzed by STATA version 12 software. Generalized estimating equation (GEE) was used to determine the factors associated with the mean change in 12 months post-treatment verbal and non-verbal neurocognition scores. Unadjusted and adjusted beta coefficients with their 95% confidence intervals were reported.ResultsA total of 48 CYPs with PBTs were enrolled, 23 (48%) of them were lost to follow-up and 10 (21%) died. The remaining 25 (52%) were reassessed 12 months after treatment. On multivariable analysis, a significant decline in verbal intelligence scores at 12 months was predicted by post-treatment seizures beta = − 20.8 (95% CI, − 38.2, − 3.4), mothers having no formal educational status and lower household monthly income. Similarly, a significant decline in perceptual reasoning scores was also predicted by post-treatment seizures beta = − 10.7 (95% CI, − 20.6, − 0.8), mothers having no formal education and having lower household monthly income. Worsening of processing speed scores at 12 months post-treatment were predicted by tumor histology, post-treatment seizures beta = − 33.9 (95% CI, − 47.7, − 20.0), lower educational status of the mother, and having lower household monthly. However, an improvement was seen in processing speed scores after surgical tumor resection.ConclusionIn this novel study, the post-treatment mean change in verbal and non-verbal neurocognition scores was associated with sociodemographic, tumor, and treatment factors. These findings may have potential implications for targeted early psychological screening of higher risk CYP with PBTs. Identification of these predictors may serve as a foundation for developing more cost-effective treatment thereby alleviating the burden of neurocognitive morbidity. However to establish generalizability, future research should prioritize larger-scale, multicountry studies. (Trial registration: ClinicalTrials.gov Identifier: NCT05709522)
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| 34. |
- Zahid, Nida, et al.
(författare)
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Psychosocial factors influencing quality of life in patients with primary brain tumors in Pakistan : an analytical cross-sectional study
- 2023
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Ingår i: BMC Research Notes. - : Springer Nature. - 1756-0500. ; 16:1
-
Tidskriftsartikel (refereegranskat)abstract
- ObjectiveDespite quality of life (QoL) being recognized as an important outcome in neuro-oncology, there is a lack of research from Pakistan where sociocultural differences may influence QoL. This study aimed to measure the QoL in patients with primary brain tumors (PBTs) and assess its association with mental health outcomes and social support.ResultsOur study included a total of 250 patients, with a median age of 42 years (range 33-54 years). The commonest brain tumors were glioma (46.8%) and meningioma (21.2). The mean global QoL of the sample was 75.73 +/- 14.9. The majority of patients had high social support (97.6%) and were not depressed (90%) or anxious (91.6%).On multivariable linear regression, global QoL was inversely associated with no or low income (beta coefficients: -8.75 to -11.84), having hypertension (-5.53), currently using a urine catheter (-13.55), having low social support (-28.16) suffering from mild (-15.31) or symptomatic (-23.84) depression, or mild anxiety (-13.22).
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| 35. |
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| 36. |
- Zara, Zeenat, et al.
(författare)
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A comparative study of DFT calculated and experimental UV/Visible spectra for thirty carboline and carbazole based compounds
- 2017
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Ingår i: Journal of Molecular Structure. - : Elsevier. - 0022-2860 .- 1872-8014. ; 1149, s. 282-298
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study of UV/Visible spectra of carboline and carbazole derivatives was conducted by employing the Density Functional Theory (DFT) approach. In this study, the geometries of ground and excited states, excitation energy and absorption spectra were estimated by using seven different DFT functional; CAM-B3LYP, B3LYP, MPW1PW91, PBE, B3PW91, WB97XD and HSE06 with 6-31G basis set. Moreover, five different basis sets 3-21G, 6-31G, DGDZVP, DGTZVP and SDD were also investigated with the CAM-B3LYP and WB97XD functional to take out the best combination of functional and basis set. CAM-B3LYP/6-31G and WB97XD/DGDZVP combination were found to have closest agreement with the experimental values of 13-carboline derivatives and carbazole derivatives, respectively. This study provided an insight about the electronic characteristics of the selected compounds and provided an effective tool for developing and designing the better UV absorber compounds.
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| 37. |
- Zara, Zeenat, et al.
(författare)
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Designing Benzodithiophene-Based Donor Materials with Favorable Photovoltaic Parameters for Bulk Heterojunction Organic Solar Cells
- 2017
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Ingår i: CHEMISTRYSELECT. - : WILEY-V C H VERLAG GMBH. - 2365-6549. ; 2:20, s. 5628-5639
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Tidskriftsartikel (refereegranskat)abstract
- Computational study on four Acceptor-Donor-Acceptor (A-D-A) type of donor molecules namely, dimethyl cyanoacetate terthiophene di(methylthiophene) benzo[1,2-b: 4,5-b'] dithiophene (DMCATDMTBDT) (M1), methylrhodanine terthiophene di (methylthiophene) benzo[1,2-b: 4,5-b'] dithiophene (MRTDMTBDT) (M2), dimethyl cyanoacetate terthiophene di (fluoromethyl thiophene) benzo[1,2-b: 4,5-b'] dithiophene (DMCATDFMTBDT) (M3), and methylrhodanine terthiophene di (fluoromethyl thiophene) benzo[1,2-b: 4,5-b'] dithiophene (MRTDFMTBDT) (M4) was carried out and their photovoltaic properties were associated with methyl cyanoacetate terthiophene di (methoxy) benzo[1,2-b: 4,5-b'] dithiophene (DCAO3TBDT) (R1) and methylrhodanine terthiophene di (methoxy) benzo[1,2-b: 4,5-b'] dithiophene (DR3TBDT) (R2). For the geometry optimization DFT functional CAM B3LYP/6-31G(d) was found to be the best choice, hence TD-CAM B3LYP/631G(d) was opted for the calculation of excited state of the molecules. M3 and M4 represented appropriate frontier molecular orbital energy levels and broad absorption band. The reorganization energies of the designed molecules illustrated excellent charge mobility property. The lower le values as compared to lambda(i) illustrate that the designed donor molecules are better electron donors. M4 was found as champion molecules with the lowest le (0.01601) value. The Voc value of M3 and M4 are 2.74 eV and 2.63 eV respectively with respect to the energy levels of PC60BM (acceptor).
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| 38. |
- Zara, Zeenat, et al.
(författare)
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Designing dibenzosilole and methyl carbazole based donor materials with favourable photovoltaic parameters for bulk heterojunction organic solar cells
- 2018
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Ingår i: Computational and Theoretical Chemistry. - : Elsevier. - 2210-271X .- 2210-2728. ; 1142, s. 45-56
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Tidskriftsartikel (refereegranskat)abstract
- Five new Acceptor-Donor-Acceptor (A-D-A) type small donor molecules (M1-M5) namely; Dimethyl cyanoacetate terthiophene di(methylthiophene) dibenzosilole (DMCAO3TBS) (M1), Dimelononitrile terthiophene di(methylthiophene) dibenzosilole (DMCNTBS) (M2), Dimethyl rhodanine terthiophene di(methylthiophene) dibenzosilole (DMRTBS) (M3), Dimelanonitrile terthiophene di(methylthiophene) methyl carbazole (DMCNTCz) (M4) and Dimethyl rhodanine terthiophene di(methylthiophene) methyl carbazole (DMRTCz) (M5) were designed and theoretically explored their electronic, photophysical and geometrical properties via DFT best functional MPW1PW91/6-311G (d,p) with respect to reference molecules Dioctyl cyanoacetate terthiophene di(octylthiophene) dioctylfluorene (DCAO3TF) (Ra) and Dioctyl cyanoacetate terthiophene di(octylthiophene) octylcarbazole (DCAO3TCz) (Rb). Among the designed donor molecules (M1-M5), M2 and M4 represented lowest band gap value (2.480 eV and 2.47 eV) with distinctive broad absorption peak at 598 nm and 601 nm in chloroform. Theoretically estimated reorganization energies of these molecules recommended excellent property of charge mobility. The designed donor molecules (M1-M5), demonstrated lower λe value with reference to their λh, showing that these molecules could be ideal candidates for the transfer of electron while M2 and M4 were found to be best molecules having lowest λe (0.006 eV and 0.005 eV respectively). Additionally the Voc of M2 and M4 are 2.01 eV and 1.85 eV respectively with respect to PCBM.
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