Vertically Segregated Polymer Blends: Their Use in Organic Electronics

Abstract

In this paper results on the formation and stability of vertically segregated polymer blend structures applied to organic‐based electronic devices are reviewed. In all examples illustrated here, phase separation in a direction normal to the substrate was obtained by a combination of surface treatment, viscosity, solvent evaporation, and blend composition control. It is found that vertically segregated blends form the optimized structure for photovoltaic devices, in which exciton dissociation is enhanced by the composition of the phases and transport of charges is improved by the position of the phases relative to the electrodes. Vertical segregation is shown to reduce leakage current and enhance charge injection and recombination in light emitting diodes resulting in highly luminescent devices. In addition, film composition and morphology analysis together with device characteristics show that the environmental stability of bottom gate polymer‐based TFTs is greatly enhanced by a self‐encapsulation method achieved with the use of a semiconductor/insulator polymer blend.

Keywords:

• vertically segregated polymer blends
• organic‐based electronic devices
• phase separation
• self‐encapsulation method

Acknowledgments

The author gratefully acknowledges J.D. MacKenzie, J.J.M. Halls, N. Corcoran, H. Snaith, and Richard Friend of the Cavendish Laboratory, University of Cambridge UK for assistance with experiments and helpful discussions as well as F. Endicott, R. Lujan, S. Ready, A. Salleo, W.S. Wong, M. Chabinyc, and R.A. Street of PARC.