Structural, optical and electrical properties of electrodeposited cadmium selenide thin films for applications in photodetector and photoelectrochemical cell

Abstract

Nanocrystalline cadmium selenide (CdSe) thin films have been deposited on indium tin oxide (ITO) coated glass substrates at room temperature (28°C) by using simple two electrode electrodeposition process. The preparative parameters such as deposition time, deposition potential, concentration of solution, pH value of electrolyte have been optimized for deposition of uniform CdSe thin films. The films were annealed at 250°C for 30min in air and characterized using X-ray diffraction, optical absorption spectrophotometer, Scanning Electron Microscope, Current–Voltage–Temperature measurements, photoconductivity and photoelectrochemical cell (PEC) measurements. XRD studies identify that the hexagonal (Wurtzite) phase present in the deposited CdSe thin films is highly oriented to [002] direction. Optical band gap is found to decrease with increase in annealing temperature. Electrical properties exhibit that the films are semiconducting. Photoresponse of the films increases with increase of exposure time. The construction of fabricated photoelectrochemical cell is CdSe|NaOH (1M)+S (1M)+Na2S (1M)|Graphite. The cell shows that the CdSe thin films have two different zones of metallic character under both dark and illumination conditions and their conversion efficiency is 1.16%.