Multifunctional photoelectrochemical logic gates based on a hemicyanine sensitized semiconductor electrode

Abstract

A new amphiphilic hemicyanine dye, (E)-1,3,3-trimethyl-2-[2-(4-N-methyl-N-hexadecylaminophenyl)ethenyl]indolinium iodide (MHID) has been synthesized and successfully transferred onto a semiconducting transparent indium-tin oxide (ITO) electrode by Langmuir–Blodgett (LB) techniques. The photoelectric conversion properties of the dye MHID monolayer fabricated ITO electrode have been investigated in a three electrode photoelectrochemical cell. The observed photocurrent strongly depends on the applied electrode potential and the concentrations of the electron acceptors and donors. By using electron acceptors and (or) donors as input and photocurrent as output, respectively, we have fabricated this artificial photoelectrochemical system as multifunctional logic gates, corresponding to a series of logic operations (YES, OR, XOR and INHIBIT). Importantly, the gates of this photoelectrochemical system have been interconnected to demonstrate computation as a half-subtractor, with Eu³⁺ and hydroquinone (H₂Q) as the two inputs and the cathodic photocurrent and the absolute value of the photocurrent as the two outputs, respectively.