Organic soluble and uniform film forming oligoethylene glycol substituted BODIPY small molecules with improved hole mobility

TitleOrganic soluble and uniform film forming oligoethylene glycol substituted BODIPY small molecules with improved hole mobility
Publication TypeJournal Article
Year of Publication2014
AuthorsSingh, S, Venugopalan, V, Krishnamoorthy, K
JournalPhysical Chemistry Chemical Physics
Volume16
Issue26
Pagination13376-13382
Date PublishedMAY
ISSN1463-9076
Abstract

Judiciously chosen side chains of conjugated molecules have a positive impact on charge transport properties when used as the active material in organic electronic devices. Amongst the side chains, oligoethylene glycols (OEGs) have been relatively unexplored due to their hydrophilic nature. OEGs also affect the smooth film formation of conjugated molecules, which preclude device fabrication. However, X-ray diffraction studies have shown that OEGs facilitate intermolecular contact, which is a desirable property for the fabrication of organic electronic devices. Thus the challenge is to design and synthesize organic solvent soluble and uniform film forming conjugated molecules with OEG side chains. We have designed and synthesized conjugated small molecules (CSMs) comprising BODIPY as acceptor and triphenylamine as donor with an OEG side chain. This molecule forms smooth films when processed from organic solvents. In order to understand the impact of the OEG side chain, we have also synthesized alkyl chain analogs. All the molecules exhibit exactly the same HOMO and LUMO energy levels, but the packing in the solid state is different. CSM with methyl side chains exhibit an inter planar distance of 4.15 A. Contrary to this, the OEG side chain containing CSM showed an inter planar spacing of 4.30 A, which is 0.2 A less than the alkyl side chain comprising CSMs. Please note that the length of the hydrophobic and hydrophilic side chains is the same. Interestingly, the OEG side chain comprising CSM showed two orders of higher hole carrier mobilities compared to all the other derivatives. The same molecule also showed an extremely low threshold voltage of -0.27 V indicating the OEG side chains' favourable interaction between substrate as well as between molecules.

DOI10.1039/c4cp01098a
Type of Journal (Indian or Foreign)Foreign
Impact Factor (IF)4.68
Divison category: 
Catalysis and Inorganic Chemistry
Polymer Science & Engineering