Fabrication of CeO2/CuI thin film with CdO as a buffer – A heterojunction diode

Abstract

Solar photovoltaics has remained a popular field despite the availability of a number of renewable energy technologies to meet global energy demands due to its ease of manufacture, materials availability, use, and low cost. In the current investigation, CuI was synthesized with the extract of Hibiscus rosa-sinensis L. flower and CeO2 & CdO were synthesized using citrate-nitrate sol-gel method. The obtained crystals were characterized using XRD, HR-TEM, HR-SEM, EDAX, UV–Vis and FTIR spectroscopic techniques. The XRD analysis of the synthesized compounds confirmed their high crystallinity and purity. The particle size of CuI, CeO2 and CdO was found to be 503.77 nm, 18.51 nm, 15.1 nm respectively from HR-TEM analysis. The CuI particles were prismatic and CeO2 & CdO were spherical in nature under HR-SEM. The band gap was calculated to be 3.03 eV for CuI, 3.43 eV for CeO2 and 2.03 eV for CdO from the UV data. The cyclic voltammetry analysis indicated that the synthesized compounds possess good electrochemical properties. CeO2/CuI heterojunction was fabricated as thin film by doctor blade method and effect of employing CdO as buffer layer was studied. The following heterojunctions - FTO/CeO2/CuI/Ag (p-n heterojunction) and FTO/CeO2/CdO/CuI/Ag (p-n-n heterojunction) were fabricated. The current-voltage (I–V) curve revealed that CeO2/CuI heterojunction exhibits better diode behavior in the presence of CdO as a buffer layer with low positive rectification ratio. Thus, with a better fabrication technique the synthesized semiconductor materials could be suitable for application in energy harvesting technology.