Effect of Intensity and Wavelength of Illumination on the Photoelectronic Properties of Nanocrystalline CdSe Thin Films

Abstract

Photoelectronic properties of nanocrystalline CdSethin films prepared by chemical bath deposition (CBD) technique at room temperature are studied taking its molar concentration as a function. Structural analysis of the deposited thin films shows that change of molarity brings a variation in the crystalline sizes of the thin films. Such thin films show suitable photoelectronic properties for the construction of different optoelectronic devices. The photocurrents are observed to be significantly defect controlled in the visible range of wavelengths. The transport mechanism for the thin films is generally a doubly activated process and the photocurrent decay characteristics curves are found to exhibit 2 different decay times which actually correspond to 2 distinct trap levels. HIGHLIGHTS The photoelectronic properties of nanocrystalline CdSe thin films deposited by CBD method are studied From the XRD of the films diffraction peaks may be indexed to diffraction basically from the (111) plane of zincblende structure The optical band gap may be varied with the molarity of the solution used for deposition Photoelectronic properties are dependent of the intensity of different monochromatic illuminations Photocurrents for the films are basically controlled by the grain boundary defects Growth and decay of photocurrent are effectively governed by different kind of traps GRAPHICAL ABSTRACT

Performance-related structural, optical, and electrical characteristics of 2 μm the CdTe-CdSe absorption layer of solar cell

“…According to the following expression [26], the experimentally measured values of R and T can be used to calculate the absorption coefficient in the strong absorption region. (5) where d stands for the sample thickness. The absorption coefficient for the various compositions is depicted as a function of photon energy in Fig.…”

“…It is generally known that the usage of solar cells contributes significantly to the global need for sustainable renewable energy [4]. II-VI group semiconductor materials are currently attracting increased attention in the realm of solar cell technology because of their intriguing physical and chemical features and applications [5,6]. Due to its close to optimal and direct optical energy bandgap, high electron affinity, large absorption coefficient, suitable lattice parameters, and low negative formation enthalpy, cadmium telluride (CdTe) is a well-known II-VI semiconductor material for producing significant amounts of terrestrial electricity [7,8].…”

Effect of particle size on optical and electrical properties of thin films – a simulation approach

“…There are endless reports of determination of optical properties of different materials developed through different physical deposition techniques in thin film form. For instances, in the year 2023 only:-Vijay et al investigated the impact of annealing temperature on the microstructure, defects, and optical properties of ZnO thin films using a sol-gel-based spin coating method and showed that particle size increases with annealing temperature, and the optical band gap reduces [22]; Banerjee et al investigated the origin of visible emissions in ZnO, focusing on excitation wavelength-dependent tuneable emission [23]; Orek et al studied the electrical, optical, and structural properties of a wurtzite-like zinc oxide nanostructure, examining the influence of quantum confinement on optical characteristics [24]; Sarmh and Borah studied nanocrystalline CdSe thin films, finding them suitable for optoelectronic devices with defect-controlled photocurrents and a doubly activated transport mechanism [25]; Gonçalves et al studied the nonlinear optical response of CdSe, revealing a predominant fifth-order nonlinear absorption behaviour and a nonlinear refractive index in good agreement with the OKG [26]; Kafashan et al investigated the impact of Cu-doping on Cadmium selenide (CdSe), highlighting its potential applications in optoelectronics due to improved absorbance, reflectance, and band gap [27].…”