Photoelectrochemical study of electrochemically synthesized CdTe thin films from acetate-anion based ionic liquid bath

摘要

Potentiostatic deposition of CdTe thin films from acetate-anion based ionic liquid, 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]) bath has been carried out at 90 degrees C. A molar concentration ratio i.e. molar Cd/Te = 2 has been taken to electrochemically synthesize CdTe films under different dynamic conditions. FE-SEM showed the formation of homogeneous CdTe films over fluorine doped tin oxide (FTO) substrates. EDX revealed the formation of nearly stoichiometric CdTe films at optimal stirring rate of similar to 400 rpm. The optical band gap of similar to 1.45eV were observed with cubic zinc blende CdTe structure. XRD, RAMAN and XPS analysis confirmed the formation of pure CdTe phase with ultra-thin oxide overlayer. Photoelectrochemical studies of CdTe photoelectrodes prepared by electrodeposition technique was investigated in K2Sx and KH2PO4. Mott-Schottky analysis demonstrated the formation of p-CdTe with a flatband (V-fb) potential of similar to 0.95V(RHE). A high photocurrent density of 1.23 mA/cm(2) has been achieved with solar conversion efficiency (eta(c)) of 1.50% for the pristine electrodeposited CdTe/FTO photocathode i.e. without surface modification, under chopped monochromatic illumination. This illustrates that the prepared CdTe photocathode can be a promising semiconductor candidate for application in photo-electrochemical hydrogen evolution from water. The use of acetate-anion based IL bath always resulted in p-type CdTe thin films. (c) 2019 Elsevier Ltd. All rights reserved.