Conjugated polymers as part of multifunctional organic/inorganic hybrid materials for photovoltaic applications

Abstract

The multifunctionality of hybrid organic-inorganic materials has been clearly demonstrated in recent years. Their application in solar- related devices is a growing research area with important technological implications. Our interest is centered on the interplay between the light-harvesting and hole-conducting properties of conjugated polymers and the wide band gap values observed from different inorganic semiconductor oxides. The materials applied in this work are the combination of semiconductor oxides like TiO2, ZnO, Nb2O5, CeO2 and TiO2-CeO 2, and different conjugated polymers like poly[2-methoxy-5-(2¿- ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) or poly(3,4- ethylenedioxythiophene) (PEDOT). Semiconductor oxides have been applied in different configurations like dense thin films, nanostructured electrodes or as nanoparticles. The conjugated polymers have been chosen depending on their light-harvesting properties (e.g. MEH-PPV) or due to their good electrical conductivity and hole conducting properties (e.g. PEDOT). We have characterized our devices in terms of Voc, Jsc, IV-curves, effect of different atmospheres and device lifetime under simulated sunlight irradiation. Tuning the different device parameters such as type of oxide applied, active layer thickness, starting materials concentration, effect of different atmospheres, effect of UV irradiation, etc., permit the fabrication of devices with well-defined properties. A brief discussion and comparison of hybrid solar cells (HSC) with solid-state Dye Sensitized Solar Cells (ss-DSC) applying nanocomposite materials based on TiO2 and PEDOT, as the electron and hole conducting materials respectively, is also included.