Optical characterization study of thin film for PV cell applications

Abstract

In this investigation n-type CdxZn1-xS and p-type PbS thin films were synthesized using chemical bath deposition (CBD) method for solar cell applications. The thin films were prepared using nitrates of cadmium and thiourea, lead and zinc. Deposition of optimised CdxZn1-xS was complete by CBD at 820 °C, in alkaline circumstances, while that of PbS ended at room temperature and both films at normal atmospheric pressure exploiting aqueous environments. Optical constant appropriate for photovoltaic applications were attempted for and to resolve this, a UV VIS IR spectrophotometer 3700 DUV was utilized. The optical band gap of deposited CdxZn1-xS films range from 2.47 eV (x = 0.6) to 2.72 eV (x = 1.0), and transmittance overhead 79% in the VIS - NIR region for the concentration range of × = 0.6 to 1.0. The band gap enlarged with increasing Zn concentration of the alloy and Cd0.6Zn0.4S sample exhibited the broadest band gap. It is observed that the concentration of zinc increased optical band gap. PbS thin films consumed a band gap of 0.89 eV and a transmittance underneath of 55% appropriate for absorber layers of solar cells. The fabricated photovoltaic cell had a small circuit current, Isc = 0.031 A, exposed voltage, Voc = 0.37 V, efficiency, η = 0.9% and a fill factor, FF = 0.66 inferring that the two materials are suitable for photovoltaic applications particularly in the VIS and IR light spectrum.