Morphology of P3HT in Thin Films in Relation to Optical and Electrical Properties

Abstract

The search for renewable and environmentally friendly energy sources has made organic electronics an interesting field of research. Semiconducting polymers stand out because they offer cheap and easy processability at a large- scale from solution, combined with impressive optoelectronic properties. Polythiophenes, in particular poly(3-hexylthiophene) (P3HT), are the most prom- inent and investigated representatives of semiconducting polymers and have been applied in various devices such as solar cells and field-effect transistors. For this class of polymers, it has been well established that the morphology of the functional layer has a significant impact on the device performance. However, transport bottlenecks are hard to determine due to the complex semicrystalline microstruc- ture, which is composed of a mixture of crystalline and amorphous domains. In order to gain a deeper understanding of the correlation between microstructure and functional properties, precise control of nucleation and growth of semicrystalline polymers such as P3HT is crucial. This article gives an overview of recent publi- cations addressing the morphology and crystallization of regioregular P3HT, both in solution and thin film, and attempts to correlate these structural features to the functional (i.e. optical and electrical) properties of the polymer.