Study of thin films for photovoltaic solar cells

Abstract

Undoped and Rare Earth Elements(Er,Yb)doped ZnO thin films were deposited onto glass substrates via sol gel dip coating technique, to investigate the effect of REEs doping concentration on the structural,Morphological and optical properties of ZnO thin films.The pH was maintained at 9 for all prepared sols by controlling the amount of Monoethanolamine (MEA).The effects of Er and Yb doping concentration on the ZnO films properties was studied by using XRD,SEM,AFM,Raman spectroscopy FTIR and UV–visible spectrophotometer .The results showed that the incorporation of Er3+and Yb3+under alkaline pH had a great effect on the ZnO properties.The XRD spectra of(Er3+,Yb3+)doped ZnO revealed that all synthesized samples exhibit a polycrystalline hexagonal wurtzite structure with no additional peak assigned to REEs.Homogenous,smooth and dense granular morphology nanostructures were revealed by AFM and SEM analysis.all samples show a low roughness value which decreases when increasing Er and Yb doping concentrations. Raman spectroscopy and FTIR analysis were found very consistent with XRD results.the optical transmittance was found to be improved by RRE(Er3+,Yb3+),A red-shift was observed in the band gap of both Er and Yb doped ZnO films with increasing doping rate. This study allowed us to get ZnO thin films with very important structural,optical properties,which are very promising in photovoltaic applications.