Effect of KI/LiF/CdCl₂on photoluminescent and electroluminescent properties of nanocrystalline (Zn-Cd)S: Cu films

Abstract

The effect of KI/LiF/CdCl 2 on photoluminescent and electroluminescent (EL) spectra have been reported for (Zn-Cd)S:Cu films. Nanocrystalline films of (Zn-Cd)S:Cu have been prepared using chemical deposition technique in aqueous alkaline bath and their subsequent condensation on substrates. Important results in terms of XRD, SEM, absorption spectra, PL and EL spectra, voltage and frequency dependence of EL brightness are presented. Also, EL brightness waves, EL decay and dependence of EL brightness on nature of electrode material are presented and discussed. SEM studies show best growth conditions in the presence of CdCl 2 . Results of XRD studies are associated to ZnS and CdS. Both the studies show average particle sizes to be in the nano order. PL and EL emissions from different films show emission peaks in the blue-green region. Results of absorption spectra show a slight change in band gaps owing to the addition of impurities. Voltage dependence of EL brightness shows effectiveness of acceleration-collision mechanism. Frequency dependence of EL brightness first shows an increase in brightness in the lower frequency range, followed by saturation at higher frequencies. Brightness waves consist of primary and secondary waves, which depend on voltage and frequency of excitation. EL cells with Al electrode give better brightness compared with cells with Ag electrodes. The lifetimes of EL emission are found to be of the order of microseconds.

Effects of copper concentration on electro-optical and structural properties of chemically deposited nanosized (Zn–Cd)S:Cu films

“…The main object of such mixing has been to facilitate the substitution of Cu in their presence because ionic radii of Zn + 2 , Cd + 2 and Cu + 2 are 0.74, 0.97 and 0.72Å, respectively. Therefore, Cu can easily be substituted in place of Cd + 2 /Zn + 2 either in substitutional or interstitial positions [5]. The luminescence emission and efficiency of semiconducting device are dependent on the concentrations and characteristics of dopant material.…”

Crystallographic, Energy Gap, Photoluminescence and Photo-Catalytic Investigation of Cu Doped Cd0.9Zn0.1S Nanostructures by Co-precipitation Method

“…The ionic radius of Zn 2+ , Cd 2+ and Cu 2+ are found to be 0.74 Å, 0.97 Å and 0.72 Å, respectively. As a result, Cu can easily replaced either as substitutional or interstitial in position of Cd 2+ [45]. When Cu is increased to higher levels, Cu related impurity or secondary phases may induced in the host lattice [46,47].…”

“…Though the comprehensive investigation on crystallographic, structural and optical properties of Zn / Cu doped CdS have been carried out [34][35][36][37][38][39][40][41][42][43][45][46][47], the detailed analysis of Zn and Cu dual doped CdS nano-system is still scanty. Therefore, the present investigation focused on the preparation of Cd 0.9 Zn 0.1 S 2+ and S 2− ions, respectively.…”

Opto-Electronics Review

“…II-VI semiconductor nanocrystals whose radii are lower than the bulk exciton Bohr radius form an intermediary class of materials between the molecular bulk states of matter. The quantum confinement of the pair of electron hole leads to an increase in the efficient bandgap with decreasing crystallite thickness, offering new ways of tuning optical and photonic properties [22]. Semiconductors of II-VI groups, such as ZnS, CdS, and ZnSe are widely used for the fabrication of solar cells, optical detectors, piezoelectric transducers, light emitting diodes (LED), and transparent UV-protection devices [23][24][25][26].…”