In Silico Modelling: Electronic Properties of Phosphorene Monoflakes and Biflakes Substituted With Al, Si, and S Heteroatoms

Abstract This contribution explores the systematic substitution of monoflakes (Mfs) and biflakes (Bfs) phosphorene with aluminum, silicon, and sulfur. All this was investigated using functional TPSS and CASSCF calculations. Al and Si substitution produces significant structural changes in both Mfs and Bfs compared to S-substituted and pristine systems. However, in Mfs, all heteroatoms generate a decrease in band gap and the ionization potentials (IP), and an increase in electron affinity (EA) in comparison with pristine phosphorene. Al doping improves the hole mobility in the phosphorene monoflake, while Si and S substitutions exhibit a similar behavior on EAs and reorganization energies. For Bfs, the interlaminar interactions Si-Si and Al-P cause structural changes and higher binding energies for Si-Bfs and Al-Bfs. Regarding the electronic properties of Bfs, substitution with Si does not produce significant variations in the band gap. However, it conduces to the formation of hole transport materials concerning its monolayer counterpart. It also is observed in Al-systems, whereas for S-complexes, no correlation was identified between the doping level and reorganization energies. Also, the substitution with Al and S leads to an opposite behavior of the band gap and IP values, while the variation in EA is similar. In summary, the nature of heteroatom and the doping degree can modify the semiconductor character and electronic properties of phosphorene mono- and the biflakes, whose trends are closely related to the atomic properties of heteroatoms considered. Overall, these computational calculations provide significant insights into the study of doped phosphorene materials.

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Band gap modulation of graphyne via chemical functionalization: a density functional theory study

Canadian Journal of Chemistry ◽

10.1139/cjc-2015-0523 ◽

2016 ◽

Vol 94 (3) ◽

pp. 229-233 ◽

Cited By ~ 8

Author(s):

R. Majidi

Keyword(s):

Density Functional Theory ◽

Band Gap ◽

Electronic Properties ◽

Density Functional ◽

Binding Energies ◽

Functional Theory ◽

Chemical Functionalization ◽

Semiconducting Properties ◽

Structural And Electronic Properties ◽

And Control

The structural and electronic properties of functionalized graphyne were studied by using density functional theory. Different concentrations of CCl2 molecules were added to α-graphyne and β-graphyne sheets. The high binding energies indicated the strong adsorption of CCl2 molecules on graphyne sheets. It was found that functionalization with CCl2 molecules can open a band gap in graphyne and functionalized graphyne sheets showing semiconducting properties. The band gap of graphyne was dependent on the concentration of adsorbed CCl2 molecules. Our results indicated that chemical functionalization of graphyne with CCl2 groups could be an effective method to modify and control the electronic properties of graphyne.

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Electronic Properties of Exciton in Mg Based II–VI Wide Band Gap Semiconducting Quantum Dots

Journal of Advanced Physics ◽

10.1166/jap.2017.1304 ◽

2017 ◽

Vol 6 (1) ◽

pp. 126-132

Author(s):

M. Asokan ◽

A. John Peter

Keyword(s):

Quantum Dots ◽

Band Gap ◽

Electronic Properties ◽

Wide Band ◽

Optical Data Storage ◽

Binding Energies ◽

Mg Alloy ◽

Optical Data ◽

Wide Band Gap ◽

Alloy Content

Electronic properties of exciton in Mg based ZnS, ZnSe and ZnTe wide band gap semiconductor cylindrical quantum dots are investigated taking into consideration of geometrical confinement effect. The confinement potentials for various concentrations of Mg alloy content in Zn1–xMgxS/MgS, Zn1–xMgxSe/MgSe and Zn1–xMgxTe/MgTe quantum dots are studied and the constant barrier height is maintained for the Mg content in all the three heterostructures (Zn0.9Mg0.1S/MgS, Zn0.25Mg0.75Se/MgSe and Zn0.09Mg0.91Te/MgTe) to obtain the exciton binding energies and the optical transition energies. The results show that the band gap increases nonlinearly with the increase of composition of Mg alloy content in the taken materials due to the positive band gap bowing parameters and the exciton binding energies in Zn0.9Mg0.1S/MgS quantum dot are found to be more than the other two dots taken for studies. Our results will be helpful for some potential applications in full colour display devices and optical data storage devices.

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Carbonyl-Terminated Quinoidal Oligothiophenes as p-Type Organic Semiconductors

Materials ◽

10.3390/ma13133020 ◽

2020 ◽

Vol 13 (13) ◽

pp. 3020

Author(s):

Takato Asoh ◽

Kohsuke Kawabata ◽

Kazuo Takimiya

Keyword(s):

Organic Semiconductors ◽

Field Effect Transistors ◽

Theoretical Calculations ◽

Energy Levels ◽

Hole Mobility ◽

Hole Transport ◽

Large Contribution ◽

Theoretical Predictions ◽

Reorganization Energies ◽

P Type

A series of quinoidal oligothiophenes terminated with carbonyl groups (nTDs, n = 2–4) are studied as p-type organic semiconductors for the active materials in organic field-effect transistors (OFETs) both by the theoretical and experimental approaches. The theoretical calculations clearly show their high-lying highest occupied molecular orbital (HOMO) energy levels (EHOMOs), small reorganization energies for hole transport (λholes), and large contribution of sulfur atoms to HOMOs, all of which are desirable for p-type organic semiconductors. Thus, we synthesized nTDs from the corresponding aromatic oligothiophene precursors and then evaluated their physicochemical properties and structural properties. These experimental evaluations of nTDs nicely proved the theoretical predictions, and the largest 4TDs in the series (4,4′′′-dihexyl- and 3′,4,4″,4′′′-tetrahexyl-5H,5′′′H-[2,2′:5′,2″:5″,2′′′-quaterthiophene]-5,5′′′-dione) can afford solution-processed OFETs showing unipolar p-type behaviors and hole mobility as high as 0.026 cm2 V−1 s−1.

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Structural properties of GaAs/InGaAs/GaAs (001) and InGaAs/GaAs (001) heterostructures and correlation with electronic properties

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176149 ◽

1990 ◽

Vol 48 (4) ◽

pp. 602-603

Author(s):

J.M. Bonar ◽

R. Hull ◽

R. Malik ◽

R. Ryan ◽

J.F. Walker

Keyword(s):

Band Gap ◽

Electronic Properties ◽

Gaas Substrate ◽

Critical Thickness ◽

Lattice Mismatch ◽

Band Offset ◽

Misfit Dislocations ◽

Gaas Substrates ◽

Gaas Structure ◽

Low X

In this study we have examined a series of strained heteropeitaxial GaAs/InGaAs/GaAs and InGaAs/GaAs structures, both on (001) GaAs substrates. These heterostructures are potentially very interesting from a device standpoint because of improved band gap properties (InAs has a much smaller band gap than GaAs so there is a large band offset at the InGaAs/GaAs interface), and because of the much higher mobility of InAs. However, there is a 7.2% lattice mismatch between InAs and GaAs, so an InxGa1-xAs layer in a GaAs structure with even relatively low x will have a large amount of strain, and misfit dislocations are expected to form above some critical thickness. We attempt here to correlate the effect of misfit dislocations on the electronic properties of this material.The samples we examined consisted of 200Å InxGa1-xAs layered in a hetero-junction bipolar transistor (HBT) structure (InxGa1-xAs on top of a (001) GaAs buffer, followed by more GaAs, then a layer of AlGaAs and a GaAs cap), and a series consisting of a 200Å layer of InxGa1-xAs on a (001) GaAs substrate.

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Defect Processes in Halogen Doped SnO2

Applied Sciences ◽

10.3390/app11020551 ◽

2021 ◽

Vol 11 (2) ◽

pp. 551

Author(s):

Petros-Panagis Filippatos ◽

Nikolaos Kelaidis ◽

Maria Vasilopoulou ◽

Dimitris Davazoglou ◽

Alexander Chroneos

Keyword(s):

Electronic Properties ◽

Tin Oxide ◽

Density Functional ◽

Structural Changes ◽

High Dielectric Constant ◽

Density Functional Theory Calculations ◽

Functional Theory ◽

Optical And Electronic Properties ◽

High Dielectric ◽

Gap States

In the present study, we performed density functional theory calculations (DFT) to investigate structural changes and their impact on the electronic properties in halogen (F, Cl, Br, and I) doped tin oxide (SnO2). We performed calculations for atoms intercalated either at interstitial or substitutional positions and then calculated the electronic structure and the optical properties of the doped SnO2. In all cases, a reduction in the bandgap value was evident, while gap states were also formed. Furthermore, when we insert these dopants in interstitial and substitutional positions, they all constitute a single acceptor and donor, respectively. This can also be seen in the density of states through the formation of gap states just above the valence band or below the conduction band, respectively. These gap states may contribute to significant changes in the optical and electronic properties of SnO2, thus affecting the metal oxide’s suitability for photovoltaics and photocatalytic devices. In particular, we found that iodine (I) doping of SnO2 induces a high dielectric constant while also reducing the oxide’s bandgap, making it more efficient for light-harvesting applications.

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Strain-induced semimetal-to-semiconductor transition and indirect-to-direct band gap transition in monolayer 1T-TiS2

RSC Advances ◽

10.1039/c5ra16877e ◽

2015 ◽

Vol 5 (102) ◽

pp. 83876-83879 ◽

Cited By ~ 23

Author(s):

Chengyong Xu ◽

Paul A. Brown ◽

Kevin L. Shuford

Keyword(s):

Band Gap ◽

Electronic Properties ◽

Plane Strain ◽

Material Properties ◽

First Principles ◽

Tensile Strain ◽

First Principles Calculations ◽

Direct Band Gap ◽

Direct Band ◽

Uniform Plane

We have investigated the effect of uniform plane strain on the electronic properties of monolayer 1T-TiS2using first-principles calculations. With the appropriate tensile strain, the material properties can be transformed from a semimetal to a direct band gap semiconductor.

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Modeling the Effect of Annealing and Regioregularity on Electron and Hole Transport Characteristics of Bulk Heterojunction Organic Photovoltaic Devices

MRS Proceedings ◽

10.1557/proc-1270-hh14-56 ◽

2010 ◽

Vol 1270 ◽

Author(s):

Shabnam Shambayati ◽

Bobak Gholamkhass ◽

Soheil Ebadian ◽

Steven Holdcroft ◽

Peyman Servati

Keyword(s):

Annealing Time ◽

Electron Mobility ◽

Bulk Heterojunction ◽

Acid Methyl Ester ◽

Hole Mobility ◽

Phase Segregation ◽

Hole Transport ◽

Trap States ◽

Current Voltage ◽

Steep Decline

AbstractIn this study, the dark current-voltage characteristics of electron-only and hole-only poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) as a function of regioregularity (RR) and annealing time is investigated using the mobility edge (ME) model. This model is used to analyze the degradation of electron and hole mobilities as a function of annealing time for 93%-RR and 98%-RR P3HT:PCBM devices. The hole mobility is almost unchanged by the RR nature of P3HT and thermal annealing. The electron mobility, however, behaves differently after annealing. The electron mobility of 98%-RR devices, which is initially higher than that of the 93%-RR devices, experiences a steep decline with annealing. Based on ME analysis, this is due to an increase in trap states in the exponential tail caused by phase segregation of solid state blends of 98%-RR polymer and PCBM. The electron mobility of 93%-RR devices increases with annealing due to an optimization of nano-phase separated morphology.

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Progress on the Synthesis and Application of CuSCN Inorganic Hole Transport Material in Perovskite Solar Cells

Materials ◽

10.3390/ma11122592 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2592 ◽

Cited By ~ 8

Author(s):

Funeka Matebese ◽

Raymond Taziwa ◽

Dorcas Mutukwa

Keyword(s):

Solar Cells ◽

Energy Levels ◽

Perovskite Solar Cells ◽

Hole Mobility ◽

Cost Effective ◽

Vital Role ◽

Hole Transport ◽

Recombination Processes ◽

Short Synthesis ◽

P Type

P-type wide bandgap semiconductor materials such as CuI, NiO, Cu2O and CuSCN are currently undergoing intense research as viable alternative hole transport materials (HTMs) to the spiro-OMeTAD in perovskite solar cells (PSCs). Despite 23.3% efficiency of PSCs, there are still a number of issues in addition to the toxicology of Pb such as instability and high-cost of the current HTM that needs to be urgently addressed. To that end, copper thiocyanate (CuSCN) HTMs in addition to robustness have high stability, high hole mobility, and suitable energy levels as compared to spiro-OMeTAD HTM. CuSCN HTM layer use affordable materials, require short synthesis routes, require simple synthetic techniques such as spin-coating and doctor-blading, thus offer a viable way of developing cost-effective PSCs. HTMs play a vital role in PSCs as they can enhance the performance of a device by reducing charge recombination processes. In this review paper, we report on the current progress of CuSCN HTMs that have been reported to date in PSCs. CuSCN HTMs have shown enhanced stability when exposed to weather elements as the solar devices retained their initial efficiency by a greater percentage. The efficiency reported to date is greater than 20% and has a potential of increasing, as well as maintaining thermal stability.

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First-Principles Study on the Stabilities, Electronic and Optical Properties of GexSn1-xSe Alloys

Nanomaterials ◽

10.3390/nano8110876 ◽

2018 ◽

Vol 8 (11) ◽

pp. 876 ◽

Cited By ~ 1

Author(s):

Qi Qian ◽

Lei Peng ◽

Yu Cui ◽

Liping Sun ◽

Jinyan Du ◽

...

Keyword(s):

Optical Properties ◽

Solar Cells ◽

Band Gap ◽

Electronic Properties ◽

First Principles ◽

Future Application ◽

First Principles Calculations ◽

Electronic And Optical Properties ◽

Direct Bandgap ◽

The Future

We systematically study, by using first-principles calculations, stabilities, electronic properties, and optical properties of GexSn1-xSe alloy made of SnSe and GeSe monolayers with different Ge concentrations x = 0.0, 0.25, 0.5, 0.75, and 1.0. Our results show that the critical solubility temperature of the alloy is around 580 K. With the increase of Ge concentration, band gap of the alloy increases nonlinearly and ranges from 0.92 to 1.13 eV at the PBE level and 1.39 to 1.59 eV at the HSE06 level. When the Ge concentration x is more than 0.5, the alloy changes into a direct bandgap semiconductor; the band gap ranges from 1.06 to 1.13 eV at the PBE level and 1.50 to 1.59 eV at the HSE06 level, which falls within the range of the optimum band gap for solar cells. Further optical calculations verify that, through alloying, the optical properties can be improved by subtle controlling the compositions. Since GexSn1-xSe alloys with different compositions have been successfully fabricated in experiments, we hope these insights will contribute to the future application in optoelectronics.

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CHANGES INDUCED IN THE SURFACE ELECTRONIC STRUCTURE OF Be(0001) AFTER Si ADSORPTION

Surface Review and Letters ◽

10.1142/s0218625x02002907 ◽

2002 ◽

Vol 09 (02) ◽

pp. 687-691

Author(s):

L. I. JOHANSSON ◽

C. VIROJANADARA ◽

T. BALASUBRAMANIAN

Keyword(s):

Electronic Structure ◽

Band Structure ◽

Band Gap ◽

Electronic Properties ◽

Surface State ◽

Core Level ◽

Clean Surface ◽

Core Level Spectrum ◽

Surface Band ◽

Surface Electronic Structure

A study of effects induced in the Be 1s core level spectrum and in the surface band structure after Si adsorption on Be(0001) is reported. The changes in the Be 1s spectrum are quite dramatic. The number of resolvable surface components and the magnitude of the shifts do decrease and the relative intensities of the shifted components are drastically different compared to the clean surface. The surface band structure is also strongly affected after Si adsorption and annealing. At [Formula: see text] the surface state is found to move down from 2.8 to 4.1 eV. The band also splits at around 0.5 Å-1 along both the [Formula: see text] and [Formula: see text] directions. At [Formula: see text] and beyond [Formula: see text] only one surface state is observed in the band gap instead of the two for the clean surface. Our findings indicate that a fairly small amount of Si in the outer atomic layers strongly modifies the electronic properties of these layers.

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