Digital Imaging of the Effect of Photoetching on the Photoresponse of n-Type Tungsten Diselenide and Molybdenum Diselenide Single Crystal Electrodes

The effect of photoetching on the photoelectrochemical behavior of n-MoSe 2 and n-WSe 2 layered compounds in contact with iodide electrolytes has been studied by the scanning microscope for semiconductor characterization (SMSC), a technique for imaging physical effects photoinduced at the semiconductor−electrolyte interface. Photocurrent images in combination with localized intensity modulated photocurrent spectroscopy (IMPS) measurements performed with the SMSC, on a micrometric scale, show that the increase of photoresponse observed after photoetching is due to the generation at the van der Waals surface of defects able to hinder surface recombination and to promote interfacial charge transfer through the covalent interaction with photogenerated triiodide ions.