Fullerene based organic solar cells

The direct conversion of the sunlight into electricity is the most elegant process to generate environmentally-friendly renewable energy. Plastic solar cells offer the prospect of flexible, lightweight, lower cost of manufacturing, and hopefully an efficient way to produce electricity from sunlight. Since the discovery of photo induced charge transfer from a conjugated polymer to C60, followed by introduction of the bulk heterojunction concept, this material combination has been extensively studied in organic solar cells leading to a power conversion efficiency approaching 6% nowadays. A typical bulk heterojunction solar cell consists of a photoactive layer sandwiched between two different electrodes. The photoactive layer is based on a blend of an electron donating material (p-type semiconductor) and an electron accepting material (n-type semiconductor) forming nanostructured bicontinuous interpenetrating networks. Although significant progress has been made for bulk heterojunction photovoltaic devices, the current efficiency of these solar cells does not guarantee (large scale) commercialization. The most commonly used n-type semiconductor in the bulk heterojunction solar cells is [60]PCBM. Up till now [60]PCBM remains the best performing soluble fullerene derivative in combination with rr-P3HT. Improving the performance and lifetime of bulk heterojunction solar cells requires careful design and material engineering, and more insight in the operation of these devices. This thesis addresses the possibility of using new fullerene derivatives in organic bulk heterojunction photovoltaic devices, and discusses the preparation, and the morphological and electrical characterization of devices made from rr-P3HT and a library of new methanofullerene