Karl Franzens University Graz
Graz University of Technology
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Karl Franzens University Graz | Graz University of Technology | |
Polymer solar cells: charge transfer states and efficiency Polymer solar cells attract considerable attention in recent years as a future, low-cost contribution to renewable energy. Polymer solar cells use a combination of two complementary organic semiconductors in a nanoscale phase-separated blend to convert sunlight into electrical power. In recent years there has been a considerable activity in this field to develop new materials and device architectures that enhance the efficiency beyond the current state of the art. The first part of the lecture will provide a brief overview of the background and the state of the art in the field of single and multi junction polymers solar cells. Despite enormous progress, these materials and their devices pose intriguing scientific questions regarding charge generation and charge collection. In the second part of the lecture, the existence and possible role of weakly bound interfacial charge transfer states will be discussed. Charge transfer interactions play a role in the ground state and in the excited state and by analyzing their energies it is possible to make refined predictions on the maximum efficiencies that can be obtained in polymer solar cells. This will show that there is significant potential for further improvements. |