Abstract

Recently, a novel approach to insert ultrahin polymer layers with well-controllable electronic properties into solution-processed optoelectronic device structures has been proposed [1]. This approach allows to establish property-function relationships, which are not accessible by the study of conventional blend device. Experiments on electrophosphorescent devices as well as Kelvin-probe experiments under illumination show that these layers are dense and exhibit a strong electron-blocking function [2]. Upon proper choice of the HOMO and LUMO level of the interlayer material, efficient recombination of charges at the interface could be realized. Comparable studies on bilayer and solar cell devices based on poly(p-phenylene vinylenes) suggest that the performance of these devices is not determined by charge transport and free carrier recombination. This supports the view that the efficiency to form free carriers is the main limiting factor.

[1] J. S. Kim, R. H. Friend, I. Grizzi, J. H. Burroughes, Appl. Phys. Lett. 87 (2006) 023506. [2] X.H. Yang, F. Jaiser, B. Stiller, D. Neher, F. Galbrecht, U. Scherf, Adv. Funct. Mater. 16 (2006) 2156