Effect of Self-Assembled Monolayers on the Performance of Organic Photovoltaic Cells

Hanène Bedis

UMAO, Faculté des Sciences de Tunis, Campus Universitaire, 2092 El-Manar I, Tunis, Tunisia.

DOI: 10.4236/jsemat.2011.12007                

Abstract

The improvement of the performance of organic photovoltaic cells (OPVCs) and the photogeneration process in these devices may occur via multiple mechanisms depending on their structure and/or architecture. For this purpose we investigate how self-assembled monolayers of thiol molecules (C₁₂H₂₅SH and 3T(CH₂)₆SH) and benzoic acid molecules (ABA and NBA) affect the efficiency and the photogeneration of free carriers in a sexithiophene based photovoltaic cells. Firstly, we provide the results of absorption spectra for samples with SAM of thiol that show there effect on orientation of 6T molecules on these structures and the organization degree of the thiol molecules on ITO substrate. Afterward, we describe from current vs. applied voltage after illumination, the enhancement of the performance of these cells. In the second, we study the effect of SAM of benzoic acids molecules on the photovoltaic behavior. A theoretical model is used for quantitative description of the open circuit voltage as a function of carrier’s generation rates at the electrodes. The results of I-V characterization under illumination show that open circuit voltage as well as short circuit current is dramatically affected by the dipolar layer. The orientation and the magnitude of dipole moment of benzoic acid molecules are the crucial factors that affect the organic photovoltaic parameters.

Keywords

SAMs, Oligothiophene, Photovoltaïc Cell, Photogeneration, Efficiency, Performance

Conflicts of Interest

The authors declare no conflicts of interest.

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