17

Photogeneration and Recombination in Polymer Solar Cells

Carsten Deibel, Andreas Baumann, and Vladimir Dyakonov

17.1 Introduction

Organic solar cells have a strong potential to complement and enhance the application areas of their inorganic counterparts [1]. They can be processed with mass production compatible printing techniques on flexible substrates at room temperature [2], leading to a low-energy footprint. The absorption coefficient of photoactive organic semiconductors is very high, leading to low material consumption. The focused efforts on research and development of these systems have led to notable increases in their performance and lifetimes. Recently, power conversion efficiency of 10% was reported [3], and lifetimes for encapsulated devices exceeding several years [4]. Even if these values remain below the corresponding figures of merit for inorganic solar cells, the lower cost structure can make organic photovoltaics attractive for a range of applications. In order to get on par with established solar cell technologies, the investigation of the fundamental mechanisms of charge photogeneration and intrinsic stability are a prerequisite for a guided device optimization. Here, we give an overview on the elementary processes determining the conversion from light to current in polymer-based organic solar cells.

The first organic solar cells were made of a single layer of organic semiconductor with two metal contacts with asymmetric work functions for the extraction ...

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