Showing 2 results for Neghabi
M. Neghabi, A. Behjat, S.m.b. Ghorashi,
Volume 4, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 4, No. 2, Summer-Fall 2010)
Abstract
ZnS/metal/ZnS (ZMZ) nanomultilayer films with Au, Ag and Cu as a metal layer have been deposited on a glass substrate by thermal evaporation and then, were annealed in air at different temperatures from 100 to 300 ºC for one hour. Several analytical tools such as X-ray diffraction, four point probe and spectrophotometer were used to study the changes in structural, electrical and optical properties of the samples. XRD patterns show that the crystallinity of structures and also grain size of particles increases with increasing the annealing temperature. Improved electrical property (a sheet resistance of 7 Ω/sq for ZnS/Au/ZnS) and considerable improvement in the transmittance curves (86% maximum transmittance for ZnS/Au/ZnS) of the samples after heat treatment at 200ºC was observed. Also, the optical constants of the ZMZ multilayer samples were calculated from transmittance and reflectance measurements. The figure of merit was applied on the ZMZ coatings and the most suitable films and annealing temperature for the application as transparent conductive electrodes were determined.
Tahereh Dirikvand, Mehdi Zadsar, Mina Neghabi, Jamshid Amighian,
Volume 16, Issue 1 (Winter-Spring 2022)
Abstract
ta charset="UTF-8" >ta charset="UTF-8" >A green microcavity organic light-emitting diode combining an Al electrode (top mirror) with a distributed Bragg reflector (bottom mirror) was designed and fabricated to improve the quality factor (more than 51) and enable high reflectance and optimal electrical properties. Experimental results indicated a remarkable increase in electroluminescence and reduction of spectral width at half maximum. Distributed Bragg reflector (DBR) films were prepared at 550°C with a surface roughness of 0.25nm (root mean square: RMS). In addition, according to SiO2/TiO2 refractive indices, they obtained the highest reflection compared to all organic or inorganic DBR devices. The reflectance peak at 591 nm is 94.4% for five pairs of SiO2/TiO2 layers indicating good agreement with theoretical simulation samples. Microcavity Organic Light-Emitting Diode (OLED) with structure: 5 pairs of SiO2/TiO2/ITO(120nm) /MoO3(5nm) /MoO3:NPB(190nm) /NPB(10nm) /Alq3(35nm) /BCP(5nm) /LiF(0.7nm) /AL(200nm) has a quality factor of more than 51, high luminous (30%), remarkable increase in electro-luminescence (EL) and reduction of the spectral full width at half maximum of 10.93nm. This is an applied research that was obtained after detailed investigations on OLED microcavities and has a practical aspect to solving the problems of designing and manufacturing electrical and optical systems such as organic display screens. The innovative aspect of research in the technical knowledge of designing and manufacturing OLED microcavities and achieving an optimal structure using metal mirrors and Bragg reflectors to achieve coherent light output is a new and up-to-date issue that has not been done in Iran so far. As an essential step toward realizing organic lasers, the proposed approach can be used to produce new light sources.
