Gigantic Photoresponse and Reversible Photoswitching in Ionic Conductivity of Polycrystalline β-AgI

Abstract

A photoinduced change in the ionic conductivity was measured for polycrystalline silver iodide (AgI) by complex impedance spectroscopy, and a three-order magnitude reduction (from gigaohms to megaohms) in the bulk resistance of β-AgI on photoexcitation was found at 77K. The bulk resistance gradually increased when the light was turned off. Reversible photoinduced switching (photoswitching) between low and high resistivity states was observed, depending on the time in the dark state. This gigantic photoinduced change in the ionic conductivity is explained in terms of distortion of the β-AgI lattice following the photoinduced generation of electron-hole pairs.