Photoelectrochemical investigations of cadmium sulphide (CdS) thin film electrodes prepared by spray pyrolysis

Polycrystalline cadmium sulphide (CdS) thin films have been prepared by spraying a mixture of an equimolar aqueous solutions of cadmium chloride and thiourea on preheated fluorine doped tin oxide (FTO) coated glass substrates at different substrate temperatures. The cell configurations n-CdS/1 M (NaOH + Na2S + S)/C were used for studying the capacitance–voltage (C–V) characteristics in dark, current–voltage (I–V) characteristics in dark and under illumination, photovoltaic power output and spectral response characteristics of the as deposited thin films. Photoelectrochemical study shows that as deposited CdS thin films exhibits n-type of conductivity. The spectral response characteristics of the films at room temperature show a prominent sharp peak at 500 nm leading to optical bandgap energy of 2.48 eV. It is found that fill factor and efficiency are maximum for photoelectrode deposited at 300 °C. This is due to low resistance; high flat band potential, maximum open circuit voltage as well as maximum short-circuit current. The measured values of efficiency (η) and fill factor (FF) are found to be 0.17% and 0.38 respectively for film deposited at 300 °C.

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► Polycrystalline CdS thin films prepared by spray pyrolysis at different substrate temperatures.
► Hexagonal crystal structure has been observed from XRD studies.
► Photoelectrochemical study shows that as deposited CdS thin films exhibits n-type of conductivity.
► It is found that fill factor and efficiency are maximum for photoelectrode annealed at 300 °C.