Simple and Versatile Molecular Donors for Organic Photovoltaics Prepared by Metal‐Free Synthesis. Issue 4 (27th November 2014)

• Record Type: Journal Article
• Authors: Diac, Andreea; Demeter, Dora; Allain, Magali; Grosu, Ion; Roncali, Jean
• Is Part Of: Chemistry. Volume 21:Issue 4(2015)
• Page Start: 1598
• Page End: 1608
• Publication Date: 2014-11-27
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201405425
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Donor–acceptor molecules (D‐π‐A) built by connecting a diphenylhydrazone block to a dicyanovinyl acceptor group via various thiophene‐based π‐conjugating spacers (<bold>1</bold>–<bold>5</bold>) were synthesized from mono‐ or dialdehydes by a simple metal‐free procedure. Cyclic voltammetry and UV/Vis absorption spectroscopy show that the extension and/or increase of the donor strength of the spacer produces a decrease of the HOMO and LUMO energy level, a red shift of the absorption spectrum and an increase of the molecular absorption coefficient. Compared to solutions, the optical spectra of spin‐cast thin films of compounds <bold>1–3</bold> show a broadening and red shift of the absorption bands, consistent with the formation of J‐aggregates. In contrast the blue shift observed for the EDOT‐containing compounds <bold>4</bold> and <bold>5</bold> suggests the presence of H‐aggregates. Solution‐cast and vacuum‐deposited films of donors <bold>1–5</bold> were evaluated in solar cells with fullerene C₆₀ as acceptor. A power‐conversion efficiency among the highest reported for bilayer devices of basic configuration was obtained with compound <bold>2</bold>. On the other hand, the results obtained with <bold>4</bold> and <bold>5</bold> suggest that the presence of EDOT in the structure can have deleterious effects on the organization and performances of the donor material.</p> </abstract>