New PhD Project Offers
2012-14-LF Towards Solution-processed Organic Photovoltaics with Higher Stability (UB1-LoF, UW-WIN)
The depleting traditional energy resources and environmental pressures have made it critical, for our survival and global socio economic growth, to develop alternative energy resources that are green, renewable and cheap. At 1x105 TW, the sun provides the earth with enough energy that well surpasses our global energy needs, making solar energy, by far, the largest renewable energy source. Use of solar energy remains nevertheless exceedingly limited due to the high manufacturing cost of traditional photovoltaic devices. The emerging technology of organic photovoltaics (OPVs) promises a breakthrough in solar energy utilization, as it has the potential to enable very low cost photovoltaic device manufacturing via cheap solution coating techniques. Despite the significant progress in this technology over the last three years, the limited durability of OPVs remains to be one of the significant barriers against large scale commercialization. A key factor in their limited stability is the limited photostability of the active materials, especially the donor material, which is usually a highly conjugated polymer.
In this project, we will pursue the use of phthalocyanine-based low molecular weight materials as donor materials for solution-processed OPVs, replacing polymers. Besides their high photoconductivity, phthalocyanines have higher ambient and photo-stability, and, as such, are expected to result in increased OPV stability. However, as they generally have limited stability in common organic solvents, their utilization in OPVs requires developing novel solvent systems and formulation agents to make them compatible with solution-coating techniques; the latter being a requirement for low cost OPV fabrication. Their use in OPVs will also require developing compatible anode buffer layers with matching energy levels for maximal hole collection. To this end, the research work will follow a path consisting of the following three interdependent yet increasingly progressive stages; (1) identifying the most optimal phthalocyanine derivatives for maximal photovoltaic performance [e.g. maximal spectral match and optical density]; (2) identifying solvent systems and formulation agents for solubilising the most suitable phthalocyanines, and developing optimal formulations of OPV active material “inks” and optical coating parameters; and (3) developing compatible anode buffer layers in order to minimize the series resistance of an OPV cell, and thereby maximize its fill factor. The research will emphasize experimental investigations at both the materials and devices levels, and will provide extensive training in state-of-the-art methodologies in material formulation technologies, thin film device fabrication techniques, and electronic material and device characterization. In these investigations, many “home made” setups will be designed and utilized (process intensive techniques…). Several nanoscale and spectroscopic facilities will be used to probe the properties of model cells and compounds (AFM, TEM, DRX, Raman, IR…).
The research will be performed in a close collaboration involving two Academic research groups [the University of Bordeaux in France and the University of Waterloo in Canada]. University of Bordeaux/IMS lab has a strong expertise in organic photovoltaic cell fabrication (normal and inverted cells into gloves box) and IV characterisations. University of Waterloo has a historical knowledge in OLED, advanced electronic device characterisations and stability study. The last partner, a joint lab with Rhodia-Solvay Company and University of Bordeaux [Rhodia-Solvay’s Lab of the Future in France] will share his expertise in formulation, physicochemistry of coating and will dedicate 0.2 FTE Rhodia engineer to follow and challenge this project.
Project Partners :
• UB1-LOF (Rhodia Solvay’s Lab of the Future): Solvents and formulations of OPV active material inks
• UB1-IMS (University of Bordeaux): OPV fabrication and characterization
• UW-WIN (University of Waterloo): Organic device physics and characterization