Fabrication and characterization of poly[(2-methoxy-5-(2′-ethyl-hexyloxy)phenylene vinylene] (MEH-PPV) Langmuir–Schaefer films and their application as photoelectrochemical cells

Abstract

The Langmuir monolayer behaviour of poly[(2-methoxy-5-(2′-ethyl-hexyloxy)phenylene vinylene] (MEH-PPV) conducting polymer in a subphase containing various anions was investigated at the air–water interface. The Langmuir–Schaefer (LS) films were prepared in deionized water that showed the minimum area per molecule, and were found to be essential for the formation of Langmuir monolayer at the air–water interface of MEH-PPV conjugated polymer. The LS films of MEH-PPV were investigated by using UV–VIS absorption, electrochemical and atomic force microscopic techniques. A uniform deposition of monolayers was shown by optical technique, whereas a higher number of monolayers resulted in the tiny island morphology in MEH-PPV LS films. The influence of concentration of anions on the redox properties of the LS films was studied by cyclic voltammetric measurements. The nature of anions in electrochemical investigation revealed the significant changes in the redox properties of the MEH-PPV LS films. The photoelectrochemical current transient of MEH-PPV LS films was compared with those obtained by the solution cast technique. This work also focused on the influence of the nature of the electrolytes, the applied potential, the type of the film and the presence of dissolved oxygen on the photoelectrochemical properties of MEH-PPV conducting polymer.