Published in

Nature Research, Scientific Reports, 1(4), 2014

DOI: 10.1038/srep05286

Links

Tools

Export citation

Search in Google Scholar

Molecular weight dependent vertical composition profiles of PCDTBT:PC71BM blends for organic photovoltaics

Journal article published in 2014 by James W. Kingsley, Pier Paolo Marchisio, Hunan Yi, Ahmed Iraqi ORCID, Christy J. Kinane, Sean Langridge, Richard L. Thompson, Ashley J. Cadby, Andrew J. Pearson, David G. Lidzey ORCID, Richard A. L. Jones, Andrew J. Parnell ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Upload
Red circle
Postprint: archiving forbidden
Green circle
Published version: archiving allowed
Upload
Policy details
Data provided by SHERPA/RoMEO

Abstract

AbstractWe have used Soxhlet solvent purification to fractionate a broad molecular weight distribution of the polycarbazole polymer PCDTBT into three lower polydispersity molecular weight fractions. Organic photovoltaic devices were made using a blend of the fullerene acceptor PC71BM with the molecular weight fractions. An average power conversion efficiency of 5.89% (peak efficiency of 6.15%) was measured for PCDTBT blend devices with a number average molecular weight of Mn = 25.5 kDa. There was significant variation between the molecular weight fractions with low (Mn = 15.0 kDa) and high (Mn = 34.9 kDa) fractions producing devices with average efficiencies of 5.02% and 3.70% respectively. Neutron reflectivity measurements on these polymer:PC71BM blend layers showed that larger molecular weights leads to an increase in the polymer enrichment layer thickness at the anode interface, this improves efficiency up to a limiting point where the polymer solubility causes a reduction of the PCDTBT concentration in the active layer.