Charge Transfer Induced Local Exciton States at High Dopant Concentration

1994 ◽  
Vol 257 (1) ◽  
pp. 251-257 ◽  
Author(s):  
A. Eilmes ◽  
P. Petelenz
Keyword(s):  
Charge Transfer ◽  
Dopant Concentration ◽  
High Dopant Concentration

A CORRESPONDING RELATION BETWEEN ELECTROLUMINESCENT INTENSITY AND THE ENERGY AND CHARGE TRANSFER IN DOPED ORGANIC ELECTROLUMINESCENT DEVICES

2008 ◽  
Vol 22 (30) ◽  
pp. 2979-2986
Author(s):  
HONG-JIAN LI ◽  
ZHI-JUN WANG ◽  
JUN-XI WANG ◽  
XUE-YONG LI ◽  
HUI XIA ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Conjugated Polymer ◽  
Fluorescence Spectra ◽  
Dopant Concentration ◽  
Quantitative Relation ◽  
Efficient Energy Transfer ◽  
Electroluminescent Devices ◽  
Efficient Energy ◽  
Hamiltonian Model ◽  
Organic Electroluminescent

In doped organic electroluminescent devices (OLEDs), the changes of the fluorescence spectra occurred due to the energy and charge transfer from guest to host. A quantitative relation between the energy and charge transfer for doping OLEDs was studied by means of a Hamiltonian model. It was found that there is a corresponding relation between the EL intensity of doped PVK and the amount of the transferred charge and the change of the energy derived from charge transfer with dopant concentration, and the more the amount of the transferred charge and the decreasing of the energy from charge transfer, the higher the EL intensity in doped OLEDs. We can deduce that the efficient energy transfer results from the transferred charge between PVK and perylene. Based on the transport mechanism of carriers in conjugated polymer, an expression of conductivity was presented. Calculated results indicated that there is also a corresponding relation between the EL intensity of doped PVK and conductivities with dopant concentration. The larger the conductivities, the higher the EL intensity in doped OLEDs.

scholarly journals The formation of polymer-dopant aggregates as a possible origin of limited doping efficiency at high dopant concentration

2018 ◽  
Vol 53 ◽  
pp. 135-140 ◽  
Author(s):  
Julie Euvrard ◽  
Amélie Revaux ◽  
Pierre-Alain Bayle ◽  
Michel Bardet ◽  
Dominique Vuillaume ◽  
...  
Keyword(s):  
Dopant Concentration ◽  
High Dopant Concentration

Model of phosphorus diffusion in silicon for highly doped solar cell emitter layer

2019 ◽  
Vol 36 (3) ◽  
pp. 104-108
Author(s):  
Wojciech Filipowski
Keyword(s):  
Solar Cell ◽  
Diffusion Process ◽  
Dopant Concentration ◽  
Phosphorus Concentration ◽  
Concentration Profiles ◽  
Content Type ◽  
Phosphorus Diffusion ◽  
Emitter Layer ◽  
Real Concentration ◽  
High Dopant Concentration

Purpose The purpose of this paper was the development of a model enabling precise determination of phosphorus concentration profile in the emitter layer of a silicon solar cell on the basis of diffusion doping process duration and temperature. Fick’s second law, which is fundamental for describing the diffusion process, was assumed as the basis for the model. Design/methodology/approach To establish a theoretical model of the process of phosphorus diffusion in silicon, real concentration profiles measured using the secondary ion mass spectrometry (SIMS) method were used. Samples with the phosphorus dopant source applied onto monocrystalline silicon surface were placed in the heat zone of the open quartz tube furnace, where the diffusion process took place in the temperature of 880°C-940°C. The measured real concentration profiles of these samples became template profiles for the model in development. Findings The model was developed based on phenomena described in the literature, such as the influence of the electric field of dopant ionized atoms and the influence of dopant atom concentration nearing the maximum concentration on the value of diffusion coefficient. It was proposed to divide the diffusion area into low and high dopant concentration region. Originality/value A model has been established which enabled obtaining a high level of consistency between the phosphorus concentration profile developed theoretically and the real profile measured using the SIMS method. A coefficient of diffusion of phosphorus in silicon dependent on dopant concentration was calculated. Additionally, a function describing the boundary between the low and high dopant concentration regions was determined.

scholarly journals ZnO1−xSxNanosphere in Ferroelectric Liquid Crystal Matrix: The Effect of Aggregation and Defects on the Dielectric and Electro-Optical Properties

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Dharmendra Pratap Singh ◽  
Swadesh Kumar Gupta ◽  
Rajiv Manohar
Keyword(s):  
Liquid Crystal ◽  
Dopant Concentration ◽  
Topological Defects ◽  
Localized Surface Plasmon ◽  
Smectic Layer ◽  
Ferroelectric Liquid Crystal ◽  
High Concentration ◽  
Crystal Matrix ◽  
Liquid Crystal Matrix ◽  
High Dopant Concentration

High concentration (5 wt %) ofZnO1−xSxnanosphere (NS) has been dispersed in the ferroelectric liquid crystal (FLC) to analyze the effect of high dopant concentration in the FLC matrix. The FLC molecules actively interact with the NS. The presence of NS enhances the photoluminescence of the pure FLC material due to the coupling of localized surface plasmon resonance from NS with FLC molecules. The high concentration of NS causes an aggregation in the FLC matrix and creates topological defects. The defects and aggregation cause the change in electro-optical and dielectric properties of the pure FLC material. The bigger size of NS as compared to the smectic layer separation causes the warping in the smectic layer. Semiconducting nature of NS also affects the conductivity of the pure FLC.

EFFECT OF OXYGEN CONTENT ON THE CRYSTAL STRUCTURE AND SUPERCONDUCTIVITY IN Fe-DOPED YBCO SYSTEM

2007 ◽  
Vol 21 (10) ◽  
pp. 1737-1743
Author(s):  
XIAOLING QIN ◽  
LINGWEI LI ◽  
SHIXUN CAO ◽  
JINCANG ZHANG
Keyword(s):  
Crystal Structure ◽  
Charge Transfer ◽  
Transition Temperature ◽  
Oxygen Content ◽  
Carrier Density ◽  
Dopant Concentration ◽  
Close Relation ◽  
Superconducting Transition ◽  
Carrier Localization ◽  
Effect Of Oxygen

The YBa 2 Cu 3-x Fe x O y(x=0, 0.1, 0.2) with different oxygen content has been studied through microstructure analysis and transport property measurements. The results show that the oxygen content has significant influence on the structure and superconductivity. Structure analysis shows that the microstructures of the YBCO system are dependent on the order of the Cu – O chains region. For Fe doped at Cu (1) site, the order of Cu – O chains have a close relation with the oxygen content y at low dopant concentration; when the dopant concentration is large enough (x≥0.2), the order of the chains could be destroyed, the structure becomes tetragonal and there seems to be no direct correlation with y. The suppression of superconducting transition temperature Tc caused by Cu (1) site substitution could be weakened by the increase in oxygen content to some extent. That is to say, Tc decreases with the decrease in y. The decrease in y not only makes the carrier density at the Cu – O chains region decrease but also forces the O (4) shifts to the Cu (1) site causing the enhancement of carrier localization at the Cu – O chains region which prevents charge transfer between the chains and planes, resulting in the decrease in Tc.

scholarly journals Effect of Cu doping on the optical property of green synthesised l-cystein-capped CdSe quantum dots

2021 ◽  
Vol 10 (1) ◽  
pp. 805-810
Author(s):  
Oluwatobi Samuel Oluwafemi ◽  
Sundararajan Parani ◽  
Thabang Calvin Lebepe ◽  
Rodney Maluleke
Keyword(s):  
Cadmium Chloride ◽  
Dopant Concentration ◽  
Temporal Evolution ◽  
Low Cost ◽  
Water Soluble ◽  
Environmentally Benign ◽  
Cdse Quantum Dots ◽  
Cu Doping ◽  
Transmission Electron ◽  
High Dopant Concentration

Abstract In the present study, the synthesis of water-soluble copper-doped CdSe nanoparticles (NPs) via a low cost, facile, and environmentally benign method is reported. Simple reagents such as selenium powder, cadmium chloride, and copper sulphate were used as selenium, cadmium, and copper precursor, respectively, while l-cysteine was used as a capping ligand without the use of an additional stabiliser. The as-synthesised copper-doped CdSe NPs were characterised using ultraviolet (UV-Vis) absorption and photoluminescence (PL) spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. By varying the dopant concentration, the temporal evolution of the optical properties and the shape of the nanocrystals were investigated. The observation and the results showed that the colour of the solution changed rapidly from orange to black, and the PL shifted to a longer wavelength at the high dopant concentration. The micrographic images revealed that the as-synthesised materials are small and could be used for bio labelling.

Effect of Dopant Concentration of N, Fe Co-Doped TiO2 on Photodegradation of Methylene Blue under Ordinary Visible Light

2014 ◽  
Vol 661 ◽  
pp. 34-38 ◽  
Author(s):  
Arman Sikirman ◽  
Jagannathan Krishnan ◽  
Elvana Nerissa Mohamad
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Physical Properties ◽  
Crystal Size ◽  
Dopant Concentration ◽  
Irradiation Time ◽  
Titanium Tetraisopropoxide ◽  
Solgel Method ◽  
High Dopant Concentration ◽  
Co Doped

The effect of dopant concentration on N, Fe co-doped TiO2 for photodegradation of methylene blue under ordinary visible light was investigated. The photocatalyst samples were prepared using solgel method with titanium tetraisopropoxide as precursor of titania. The dopant concentrations were varied from 0.50% and 1.0% and the calcinations temperature was fixed at 600oC. The prepared photocatalysts were characterized using XRD and FTIR to determine their physical properties. The results from XRD proved that photocatalyst with dopant concentration of 1.0% N, 1.0% Fe-TiO2 showing highly desirable properties in phase and crystal size. The results from FTIR revealed the presence of both the dopants in the samples. The effectivity of photocatalysts was tested by performing a standard batch photocatalytic degradation experiment with methylene blue as a model pollutant under ordinary visible light. The result showed that photocatalyst with high dopant concentration for both nitrogen and ferrum dopant (1.0 % N, 1.0% Fe-TiO2) yielded a maximum of 80.50% methylene blue degraded within five hours of irradiation time.

Sputtered Nb- and Ta-doped TiO2 transparent conducting oxide films on glass

2007 ◽  
Vol 22 (10) ◽  
pp. 2832-2837 ◽  
Author(s):  
Meagen A. Gillispie ◽  
Maikel F.A.M. van Hest ◽  
Matthew S. Dabney ◽  
John D. Perkins ◽  
David S. Ginley
Keyword(s):  
Dopant Concentration ◽  
Anatase Phase ◽  
Transparent Conducting Oxide ◽  
Rf Magnetron Sputtering ◽  
Oriented Crystal ◽  
Glass Substrates ◽  
Transparent Conducting ◽  
High Dopant Concentration ◽  
The Difference ◽  
Substrate Temperatures

Radio frequency (rf) magnetron sputtering is used to deposit Ti0.85Nb0.15O2 and Ti0.8Ta0.2O2 films on glass substrates at substrate temperatures (TS) ranging from ∼250 to 400 °C. The most conducting Nb-doped TiO2 films were deposited at TS = 370 °C, with conductivities of ∼60 S/cm, carrier concentrations of 1.5 × 1021 cm−3 and mobilities <1 cm2/V·s. The conductivity of the films was limited by the mobility, which was more than 10 times lower than the mobility for films deposited epitaxially on SrTiO3. The difference in properties is likely caused by the randomly oriented crystal structure of the films deposited on glass compared with biaxially textured films deposited on SrTiO3. The anatase phase could not be stabilized in the Ta-doped TiO2 films, likely because of the high dopant concentration.

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