Structure-Property Correlation of Electron Transport Materials in Organic Devices
type: CreativeWork
description: This dissertation deals with organic semiconductors as electron acceptor (n-type) materials in bulk heterojunction (BHJ) solar cells. Important features of an electron acceptor are strong visible light absorption, sufficient high electron mobility and appropriate energy levels with respect to the donor. Furthermore, the blend morphology of donor and acceptor is crucial for the device performance. Within this thesis, the synthesis and characterization of novel n-type polymers is reported and various techniques to evaluate the above mentioned parameters for n-type small molecules and polymers are presented. The aim was to investigate the impact of chemical structure on the optical and electronic properties and morphology of these semiconductors. Successful strategies how to control and improve light harvesting, electron mobility, blend morphology and solar cell performance were identified. The fundamental question of charge transport properties of the materials was addressed by fabricating single carrier devices using the SCLC (space-charge limited currents) method. The morphology was primarily investigated by atomic force microscopy (AFM) and X-ray diffraction (XRD). The first part of this thesis focuses on perylene imide based small molecules and polymers. The side groups of a series of N-substituted perylene bisimides (PBI) were found to play a crucial role on crystallinity and charge transport. The nature of the side groups had great impact on the crystalline structure and electron mobility. When hydrophilic oligoethylenglycol (OEG) side groups were present, the perylene molecules aligned in highly ordered hexagonal or lamellar columns and realized high electron mobilities of up to 7∙10E-3 cm2V-1s-1, while the perylene derivative with only hydrophobic alkyl chains only showed 3∙10E-5 cm2V-1s-1. The substituents at the perylene core also had a major impact on the blend morphology of OPV devices when these materials were used in combination with a donor polymer. Her…
abstract: This dissertation deals with organic semiconductors as electron acceptor (n-type) materials in bulk heterojunction (BHJ) solar cells. Important features of an electron acceptor are strong visible light absorption, sufficient high electron mobility and appropriate energy levels with respect to the donor. Furthermore, the blend morphology of donor and acceptor is crucial for the device performance. Within this thesis, the synthesis and characterization of novel n-type polymers is reported and various techniques to evaluate the above mentioned parameters for n-type small molecules and polymers are presented. The aim was to investigate the impact of chemical structure on the optical and electronic properties and morphology of these semiconductors. Successful strategies how to control and improve light harvesting, electron mobility, blend morphology and solar cell performance were identified. The fundamental question of charge transport properties of the materials was addressed by fabricating single carrier devices using the SCLC (space-charge limited currents) method. The morphology was primarily investigated by atomic force microscopy (AFM) and X-ray diffraction (XRD). The first part of this thesis focuses on perylene imide based small molecules and polymers. The side groups of a series of N-substituted perylene bisimides (PBI) were found to play a crucial role on crystallinity and charge transport. The nature of the side groups had great impact on the crystalline structure and electron mobility. When hydrophilic oligoethylenglycol (OEG) side groups were present, the perylene molecules aligned in highly ordered hexagonal or lamellar columns and realized high electron mobilities of up to 7∙10E-3 cm2V-1s-1, while the perylene derivative with only hydrophobic alkyl chains only showed 3∙10E-5 cm2V-1s-1. The substituents at the perylene core also had a major impact on the blend morphology of OPV devices when these materials were used in combination with a donor polymer. Her…
author: Muth, Mathis-Andreas
date published: 2013-06-25
date modified: 2026-07-27T18:49:02Z
provider: Universität Bayreuth
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Universität Bayreuth