Controlling Proton Conductivity with Light: A Scheme Based on Photoacid Doping of Materials
By Haghighat, Shima; Ostresh, Sarah; Dawlaty, Jahan M.
Published in The Journal of Physical Chemistry B
2016
Abstract
Transducing light energy to changes in material properties is central to a large range of functional materials, including those used in light harvesting. In conventional semiconductors, photoconductivity arises due to generation of mobile electrons or holes with light. Here we demonstrate, to our knowledge for the first time, an analogue of this effect for protons in an organic polymer solution and in water. We show that when a material is doped with photoacids, light excitation generates extra mobile protons that change the low-frequency conductivity of the material. We measure such change both in poly(ethylene glycol) (PEG) and in water sandwiched between two transparent electrodes and doped with a well-known photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS). The complex impedance of the material is measured over a range of 0.1 Hz