Reflection loss minimization for a ZnO/CdS/CuInSe₂ photovoltaic cell

A photovoltaic cell, based on copper and indium selenide (CuInSe₂) thin layers, with a good efficiency can be achieved by simple, easy to implement and low cost techniques. The high refractive index materials used as absorbers in photovoltaic cells cause high reflection losses (about 30%). Thin CdS and ZnO films that are, respectively, the buffer layer and the window of the cell have lower indices and are naturally suited to antireflective applications. Also, a suitable choice of the film thickness leads to minimization of reflection losses, resulting in a significant improvement of the photovoltaic efficiency. The aim of this work is to provide easy solutions that reduce reflection losses to less than 4% while respecting technological constraints

New insight into the effect of nozzle diameter on the properties of sprayed ZnO thin films

International audienceZinc oxide (ZnO) nanofibers and nanopetals were successfully deposited onto mesoporous silicon (meso-PSi), silicon, and glass substrates using zinc acetate via Spray Pyrolysis method. Electrochemical etching of the P-type (100) silicon wafer was used to prepare the mesoporous silicon layer. The effects of nozzle diameter and substrate type on the morphological, structural, and optical properties were investigated using XRD, SEM, EDX techniques, FT-IR, and UV-Vis spectrometry. Scanning Electron Microscopy (SEM) confirms the meso-PSi morphology with a diameter varying from 20 nm to 45 nm and illustrates the prepared ZnO nanostructures. EDX results show that the ratio of Zn:O is found to be similar to 1:1 for the 3-mm diameter when the oxygen is much higher than the Zn element in the 18-mm diameter. XRD measurements indicated that all films show a hexagonal Wurtzite structure with a variation of crystallographic properties and orientation according to the prepared morphology. The mean value of the crystallite size is 14.27nm for the 3-mm diameter and 19.01 nm for the 18-mm diameter. The variation in the morphological characteristics of the deposited ZnO leads to a variation in the optical properties of the sprayed ZnO thin films. The layers bandgap energy (Eg) was estimated to be 3.28 and 3.26 eV for the ZnO layers prepared by 18-mm and 3-mm nozzle diameters, respectively. This study is also helpful for subsequent studies on the tailoring of morphology and ZnO growth control on PSi substrates