scholarly journals Investigations of Different Phases Responsible for Changes in Optical Properties of Organic Semiconducting Device Material Thin Films

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Vivek Kumar Shukla ◽  
Jaya Maitra
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Organic Semiconductors ◽  
Green Light ◽  
Green Emission ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Deposition Parameters ◽  
Hydroxy Quinoline ◽  
Deposited Films

The environment sensitivity of organic semiconductors may change their molecular structure and hence optical properties. Exploiting this concept, experiments were performed on a green light emitting material bis(8-hydroxy quinoline)Zinc, (Znq2) used in organic light emitting diodes (OLEDs). Thin films were deposited at varying deposition parameters, and their properties were compared. We investigated that as deposited films have a significant component of Znq2 tetramer out of two known forms, that is, dihydrate and anhydrous tetramer (Znq2)4, the films deposited at lower deposition rates have higher anhydrous content. The degradation of thin film is shown, that changes the optical properties of film from green emission to blue which may be due to water adsorption and crystallization.

Synthesis and Optical Properties of Donor-Accepter Organic Conjugated Molecules Composed of Fluorene and Phenothiazine

2014 ◽  
Vol 1061-1062 ◽  
pp. 296-300
Author(s):  
Ze Biao Tang ◽  
Xiao Xia Sun ◽  
Pei Lin Zhang
Keyword(s):  
Optical Properties ◽  
Fluorescence Spectra ◽  
Organic Molecules ◽  
Green Light ◽  
Organic Light Emitting Diodes ◽  
Conjugated Molecules ◽  
Strong Emission ◽  
Light Emitting ◽  
Conjugated Organic Molecules ◽  
Donor Acceptor

Novel donor-acceptor conjugated organic molecules composed of central fluorene and phenothiazine units and aldehyde terminal groups have been designed and constructed via the Vilsmeier-Haack reaction. Optical properties of the resulting molecules were examined by UV-vis and fluorescence spectroscopies. The fluorescence spectra of the molecules in the solid state show strong emission peaks in the violet, blue, cyan and green light regions. Thus, the molecules are expected to be promising light-emitting materials for organic light-emitting diodes applications.

OPTICAL PROPERTIES OF GaInN/GaN MULTI-QUANTUM WELL STRUCTURE AND LIGHT EMITTING DIODE GROWN BY METALORGANIC CHEMICAL VAPOR PHASE EPITAXY

2007 ◽  
Vol 17 (01) ◽  
pp. 81-84
Author(s):  
J. Senawiratne ◽  
M. Zhu ◽  
W. Zhao ◽  
Y. Xia ◽  
Y. Li ◽  
...  
Keyword(s):  
Optical Properties ◽  
Quantum Well ◽  
Stark Effect ◽  
Light Emitting Diode ◽  
Chemical Vapor ◽  
Green Emission ◽  
Luminescence Spectroscopy ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Multi Quantum Well

Optical properties of green emission Ga 0.80 In 0.20 N/GaN multi-quantum well and light emitting diode have been investigated by using photoluminescence, cathodoluminescence, electroluminescence, and photoconductivity. The temperature dependent photoluminescence and cathodoluminescence studies show three emission bands including GaInN/GaN quantum well emission centered at 2.38 eV (~ 520 nm). The activation energy of the non-radiative recombination centers was found to be ~ 60 meV. The comparison of photoconductivity with luminescence spectroscopy revealed that optical properties of quantum well layers are strongly affected by the quantum-confined Stark effect.

Electrophoretic Deposition of Titania Thin Films: Influence of Deposition Time on Microstructural and Optical Properties of the Coatings

2013 ◽  
Vol 829 ◽  
pp. 917-921
Author(s):  
Saber Ghannadi ◽  
Hossein Abdizadeh ◽  
Mohammad Reza Golobostanfard
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Electrophoretic Deposition ◽  
Deposition Time ◽  
Colloidal Suspension ◽  
Vis Spectroscopy ◽  
Titania Films ◽  
Titania Sol ◽  
Deposited Film ◽  
Deposited Films

Titania thin films were prepared by electrophoretic deposition at various deposition times (1, 5 and 10 min) in constant applied potential (5 V). For this purpose, modified titania sol was prepared as a colloidal suspension. The influence of deposition time on the thickness and optical properties of titania films was investigated. Scanning electron microscope images illustrate compact and homogeneous titania films deposited on FTO substrates. The results show that the film thickness increases with increasing the deposition time. It could be inferred from UV-Vis spectroscopy that increasing the thickness of deposited film causes higher absorbance at UV region. Also, increasing the deposition time from 1 to 5 min leads to increase in optical band gap of the deposited films.

Influence of Substrate Temperature on Structural and Optical Properties of Co-Evaporated Cu2SnS3/ITO Thin Films

2022 ◽  
Vol 1048 ◽  
pp. 189-197
Author(s):  
Tippasani Srinivasa Reddy ◽  
M.C. Santhosh Kumar
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Substrate Temperature ◽  
Indium Tin Oxide ◽  
Nir Spectroscopy ◽  
Stoichiometric Ratio ◽  
Tin Sulfide ◽  
Structural And Optical Properties ◽  
Average Grain Size ◽  
Deposited Films

In this study report the structural and optical properties of Copper Tin Sulfide (Cu2SnS3) thin films on indium tin oxide (ITO) substrate using co-evaporation technique. High purity of copper, tin and sulfur were taken as source materials to deposit Cu2SnS3 (CTS) thin films at different substrate temperatures (200-350 °C). Further, the effect of different substrate temperature on the crystallographic, morphological and optical properties of CTS thin films was investigated. The deposited CTS thin films shows tetragonal phase with preferential orientation along (112) plane confirmed by X-ray diffraction. Micro-Raman studies reveled the formation of CTS thin films. The surface morphology, average grain size and rms values of the deposited films are examined by Scanning electron spectroscopy (SEM) and Atomic Force Microscopy (AFM). The Energy dispersive spectroscopy (EDS) shows the presence of copper, tin and sulfur with a nearly stoichiometric ratio. The optical band gap (1.76-1.63 eV) and absorption coefficient (~105 cm-1) of the films was calculated by using UV-Vis-NIR spectroscopy. The values of refractive index, extinction coefficient and permittivity of the deposited films were calculated from the optical transmittance data.

Luminescence Properties of InGaN/GaN Green Light-Emitting Diodes with Si-Doped Graded Short-Period Superlattice

2021 ◽  
Vol 21 (11) ◽  
pp. 5648-5652
Author(s):  
ll-Wook Cho ◽  
Bom Lee ◽  
Kwanjae Lee ◽  
Jin Soo Kim ◽  
Mee-Yi Ryu
Keyword(s):  
Optical Properties ◽  
Decay Time ◽  
Stark Effect ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Time Resolved ◽  
Light Emitting ◽  
Quantum Confined Stark Effect ◽  
Short Period ◽  
Si Doped

The optical properties of InGaN/GaN green light-emitting diodes (LEDs) with an undoped graded short-period superlattice (GSL) and a Si-doped GSL (SiGSL) were investigated using photoluminescence (PL) and time-resolved PL spectroscopies. For comparison, an InGaN/GaN conventional LED (CLED) without the GSL structure was also grown. The SiGSL sample showed the strongest PL intensity and the largest PL peak energy because of band-filling effect and weakened quantum- confined stark effect (QCSE). PL decay time of SiGSL sample at 10 K was shorter than those of the CLED and GSL samples. This finding was attributed to the oscillator strength enhancement by the reduced QCSE due to the Coulomb screening by Si donors. In addition, the SiGSL sample exhibited the longest decay time at 300 K, which was ascribed to the reduced defect and dislocation density. These results indicate that insertion of the Si-doped GSL structure is an effective strategy for improving the optical properties in InGaN/GaN green LEDs.

Sign in / Sign up

Export Citation Format

Share Document