Influence of the processing conditions on charge transfer and transport properties in poly(2-methoxy-5-(2′-ethylhexyloxy)1-4-phenylenevinylene):C60 composites for photovoltaics

• Published in: Thin solid films Vol. 516; no. 7; pp. 1578 - 1583
• Main Authors: Ltaief, A., Bouazizi, A., Davenas, J., Alcouffe, P.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 15-02-2008; Elsevier Science
• Subjects: Applied sciences; Atomic force microscopy (AFM); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conjugated polymer; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Energy; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Natural energy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoluminescence; Photovoltaic; Photovoltaic conversion; Physics; Polymers; organic compounds; Solar cells. Photoelectrochemical cells; Solar energy; Specific materials; Spin coating; Atomic force microscopy (AFM); Conjugated polymer; Photovoltaic; Spin coating; Photoluminescence; Phenylenevinylene polymer; Atomic force microscopy; Scanning electron microscopy; Transport properties; Electrical properties; Photovoltaic cell; Thin films; Composite materials; Morphology; Optical properties; Phase separation; Fullerenes; Percolation; Spin-on coating; Charge transfer; Sol-gel process
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2007.07.191

Polymer-based photovoltaic devices have been elaborated by blending the conjugated polymer, poly(2-methoxy-5-(2′-ethylhexyloxy)1-4-phenylenevinylene) (MEH-PPV) with the buckminsterfullerene, C60. The solvent used has a main influence on the optical and electrical properties of the photoactive layers. This could be attributed to different dispersion abilities of C60 in the polymer layers shown by Atomic Force Microscopy and Scanning Electron Microscopy. Its effect on the transfer and transport properties has been studied. Thin film processing conditions have been modified by the preparation of blends of solutions of the polymer in Tetrahydrofuran and fullerene in Ortho-dichlorobenzene. The resulting spin casted layers show improved morphologies implying better dispersion of the fullerenes and increased short circuit currents. A decrease in the fullerene critical concentration to form percolation paths has been demonstrated. The improvement of the photovoltaic properties of the MEH-PPV/C60 composites has been attributed to the nanosized fullerene domains formed upon phase separation. We used optical spectroscopy to study the charge transfer efficiency and electrical measurements to investigate charge transport properties in MEH-PPV:C60.