Energy gaps in organic semiconductors derived from electrochemical data

1980 ◽  
Vol 33 (8) ◽  
pp. 1717 ◽  
Author(s):  
LE Lyons
Keyword(s):  
Band Gap ◽  
Organic Semiconductors ◽  
Aromatic Hydrocarbons ◽  
Solvation Energy ◽  
Dielectric Constants ◽  
Ion Solvation ◽  
Reduction Potentials ◽  
Energy Gaps ◽  
Organic Solid ◽  
Ionization Model

The band gap, EG, of an organic solid can be estimated by adding the magnitudes of oxidation and reduction potentials of the compound in solution, plus a correction to the ion solvation energy which allows for the different dielectric constants of solvent and solid. Values of EG for 30 organic solids have been estimated. ��� The auto-ionization model, previously used for aromatic hydrocarbons, is applied to dyes and chlorophylls. The values of EG are used to interpret various existing results on photoconduction and semiconduction in dyes and chlorophylls.

scholarly journals Electronic and optical properties of vacancy ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; and X = Cl, Br, I): a first principles study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Faizan ◽  
K. C. Bhamu ◽  
Ghulam Murtaza ◽  
Xin He ◽  
Neeraj Kulhari ◽  
...  
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
First Principles ◽  
Density Functional ◽  
Perovskite Solar Cells ◽  
Dielectric Constants ◽  
Maximum Efficiency ◽  
Exchange Potential ◽  
Double Perovskites ◽  
Electronic And Optical Properties

AbstractThe highly successful PBE functional and the modified Becke–Johnson exchange potential were used to calculate the structural, electronic, and optical properties of the vacancy-ordered double perovskites A2BX6 (A = Rb, Cs; B = Sn, Pd, Pt; X = Cl, Br, and I) using the density functional theory, a first principles approach. The convex hull approach was used to check the thermodynamic stability of the compounds. The calculated parameters (lattice constants, band gap, and bond lengths) are in tune with the available experimental and theoretical results. The compounds, Rb2PdBr6 and Cs2PtI6, exhibit band gaps within the optimal range of 0.9–1.6 eV, required for the single-junction photovoltaic applications. The photovoltaic efficiency of the studied materials was assessed using the spectroscopic-limited-maximum-efficiency (SLME) metric as well as the optical properties. The ideal band gap, high dielectric constants, and optimum light absorption of these perovskites make them suitable for high performance single and multi-junction perovskite solar cells.

Advantages of naphthalene as building block for organic solid state laser dyes: Smaller energy gaps and enhanced stability

2021 ◽  
Author(s):  
Yuya Oyama ◽  
Masashi Mamada ◽  
Akihiro Kondo ◽  
Chihaya Adachi
Keyword(s):  
Solid State ◽  
Spontaneous Emission ◽  
Building Block ◽  
Solid State Laser ◽  
Laser Dyes ◽  
Energy Gaps ◽  
Organic Solid ◽  
Organic Laser ◽  
Yellow Region ◽  
Enhanced Stability

Organic laser dyes exhibiting very low amplified spontaneous emission (ASE) thresholds in green and yellow region were developed based on a stilbene structure which is often used for the blue...

Dithienylbenzobis(thiadiazole) based organic semiconductors with low LUMO levels and narrow energy gaps

2010 ◽  
Vol 46 (19) ◽  
pp. 3265 ◽  
Author(s):  
Takahiro Kono ◽  
Daisuke Kumaki ◽  
Jun-ichi Nishida ◽  
Shizuo Tokito ◽  
Yoshiro Yamashita
Keyword(s):  
Organic Semiconductors ◽  
Energy Gaps

Band gap tuning and p to n-type transition in Mn-doped CuO nanostructured thin films

2022 ◽  
Vol 43 (1) ◽  
pp. 012801
Author(s):  
R. Rahaman ◽  
M. Sharmin ◽  
J. Podder
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Spray Pyrolysis Technique ◽  
Band Gap Energy ◽  
Dielectric Constants ◽  
X Rays ◽  
Electron Effective Mass ◽  
Mn Doping ◽  
Type Transition ◽  
Mn Doped

Abstract Here we discuss the synthesis of copper (II) oxide (CuO) and manganese (Mn)-doped CuO thin films varying with 0 to 8 at% Mn using the spray pyrolysis technique. As-deposited film surfaces comprised of agglomerated spherical nanoparticles and a semi-spongy porous structure for 4 at% Mn doping. Energy dispersive analysis of X-rays confirmed the chemical composition of the films. X-ray diffraction spectra showed a polycrystalline monoclinic structure with the predominance of the ( 11) peak. Optical band gap energy for direct and indirect transitions was estimated in the ranges from 2.67–2.90 eV and 0.11–1.73 eV, respectively. Refractive index and static dielectric constants were computed from the optical spectra. Electrical resistivity of CuO and Mn-doped CuO (Mn:CuO) thin films was found in the range from 10.5 to 28.6 Ω·cm. The tiniest electron effective mass was calculated for 4 at% Mn:CuO thin films. P to n-type transition was observed for 4 at% Mn doping in CuO films. Carrier concentration and mobility were found in the orders of 1017 cm–3 and 10–1 cm2/(V·s), respectively. The Hall coefficient was found to be between 9.9 and 29.8 cm3/C. The above results suggest the suitability of Mn:CuO thin films in optoelectronic applications.

scholarly journals Effect of Dopant Concentration on the Structural, Optical and Sensing Properties of (SnO2)1-x(TiO2:CuO)x Sprayed Films

2019 ◽  
Vol 16 (2) ◽  
pp. 0361
Author(s):  
Mahmood Et al.
Keyword(s):  
Optical Properties ◽  
Band Gap ◽  
Energy Band ◽  
Spray Pyrolysis Technique ◽  
Single Crystal Silicon ◽  
Dielectric Constants ◽  
Energy Band Gap ◽  
Crystal Silicon ◽  
X Ray ◽  
Regular Manner

      Spray pyrolysis technique was subjected to synthesized (SnO2)1-x (TiO2: CuO) x Thin films on different substrates like glass and single crystal silicon using. The structure of the deposited films was studied using x-ray diffraction. A more pronounced diffraction peaks of SnO2 while no peaks of (CuO , TiO2 ) phase appear in the X-ray profiles by increasing of the content of (TiO2 , CuO) in the sprayed films. Mixing concentration (TiO2 , CuO) influences on the size of the crystallites of the SnO2 films ,the size of crystallites of the spray paralyzed oxide films change in regular manner by increasing of (TiO2 , CuO) amount. The effect of mixing concentration on the optical properties of the films was also investigated. The reflectance and transmittance spectra  in the wavelength range (300-1100) nm were employed to determine the optical properties such as energy band gap (Eg) and refractive index (n),  extinction coefficient  (k) , real and imaginary parts of dielectric constants (ε1, ε2) for (SnO2)1-x(TiO2:CuO)x films. The energy band gap omit of which showed reduction from (3.65 to 2.2) eV by reducing of SnO2 amount from (100 to 70) % .The reduction of energy band gap was ascribed to the new tail states introduced in the band gap of tin oxide. The sensitivity of the prepared sensor film was determined resistance difference of the films when exposed to oxidizing gas. The data declared that the mixed SnO2 films have better sensitivity in comparison with unmixed films.

scholarly journals Energy Gaps in BN/GNRs Planar Heterostructure

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5079
Author(s):  
Jinyue Guan ◽  
Lei Xu
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Band Gap ◽  
Lattice Mismatch ◽  
Tight Binding ◽  
Graphene Nanoribbon ◽  
Band Gaps ◽  
Energy Gaps ◽  
Local Potentials

Using the tight-binding approach, we study the band gaps of boron nitride (BN)/ graphene nanoribbon (GNR) planar heterostructures, with GNRs embedded in a BN sheet. The width of BN has little effect on the band gap of a heterostructure. The band gap oscillates and decreases from 2.44 eV to 0.26 eV, as the width of armchair GNRs, nA, increases from 1 to 20, while the band gap gradually decreases from 3.13 eV to 0.09 eV, as the width of zigzag GNRs, nZ, increases from 1 to 80. For the planar heterojunctions with either armchair-shaped or zigzag-shaped edges, the band gaps can be manipulated by local potentials, leading to a phase transition from semiconductor to metal. In addition, the influence of lattice mismatch on the band gap is also investigated.

New tailored organic semiconductors thin films for optoelectronic applications

2021 ◽  
Author(s):  
Dinesh Pathak ◽  
Sanjay Kumar ◽  
Sonali Andotra ◽  
Jibin Thomas ◽  
Navneet Kaur ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cell ◽  
Optical Absorption ◽  
Band Gap ◽  
Organic Semiconductors ◽  
Low Cost ◽  
Organic Thin Film ◽  
Vis Spectroscopy ◽  
Carbon Based

In this study, we have investigated new tailored organic semiconductors materials for the optoelectronic application, such as organic solar cells. The carbon-based organic semiconductor material has promising advantages in organic thin-film form. Moreover, due to its low cost, organic thin-films are suitable and cheaper than inorganic thin-film. The band gap of organic semiconductors materials can be tuned and mostly lies between 2.0eV to 4eV and the optical absorption edge of organic semiconductors typically lies in between 1.7eV to 3eV. They can be easily tailored by modifying the carbon chain and legends and looks promising for engineering the band gap to harness solar spectrum. In this work, with new tailored organic semiconductors the solution route is explored which is low cost processing method. (Anthracen-9-yl) methylene naphthalene-1-amine, 4-(anthracen-9-ylmethyleneamino)-1,5dimethyl-2-phenyl-1H-pyrazol-3-one and N-(anthracen-9-ylmethyl)-3,4-dimethoxyaniline thin-films are processed by spin coating method with changing concentration such as 0.05 wt% and 0.08 wt%. Thin films of Organic semiconductors were prepared on glass substrate and annealed at 55°C. The structural and optical behaviour of (Anthracen-9-yl) methylene naphthalene-1-amine, 4-(anthracen-9-ylmethyleneamino)-1,5dimethyl-2-phenyl-1H-pyrazol-3-one and N-(anthracen-9-ylmethyl)-3,4-dimethoxyaniline organic semiconductors thin films is studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and UV-Visible Spectroscopy technique. The XRD data of synthesized sample suggests the Nano crystallinity of the Organic layers. The SEM micrographs shows the dense packing when we increase the wt% 0.05 to 0.08. Analysis of the optical absorption measurements found that the engineered band gap of synthesized thin films are 2.18eV, 2.35eV, 2.36eV, 2.52eV and 2.65eV which suggest suitability for applications of Optoelectronic devices such as solar cell. Such light weight, eco-friendly and disposable new carbon based materials seems to have potential to replace other traditional hazardous heavy materials for future eco-friendly flat fast electronics. Keywords: Thin-film, solar cell, tailored organic semiconductors, XRD, SEM, UV-Vis spectroscopy.

Selective Transmission of Electromagnetic Wave by Using Diamond Photonic Crystals with Graded Lattice Spacing

2006 ◽  
Vol 45 ◽  
pp. 1139-1144
Author(s):  
Soshu Kirihara ◽  
Yoshinari Miyamoto
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Electromagnetic Waves ◽  
Lattice Spacing ◽  
Three Dimensional ◽  
Dielectric Constants ◽  
Microwave Antenna ◽  
Diamond Structure ◽  
Band Calculation ◽  
Graded Lattice

Three-dimensional electromagnetic or photonic crystals with periodic variations of the dielectric constants were fabricated by using a rapid prototyping method called stereolithography. Millimeter-order epoxy lattices with a diamond structure were designed to reflect electromagnetic waves by forming an electromagnetic band gap in GHz range. Titania based ceramic particles were dispersed into the lattice to control the dielectric constant. The diamond lattice structures formed the perfect band gap reflecting electromagnetic waves for all directions. The location of the band gap agreed with the band calculation using the plane wave propagation method. The diamond structures with graded lattice spacing were successfully fabricated as well, resulting in the directional transmission of microwaves. The stretching ratio of the lattice spacing in the crystal structure was changed according to the electromagnetic band calculation. A microwave antenna head composed of the diamond structure with graded lattice spacing was fabricated which achieved the unidirectional transmission.

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