%0 Journal Article
%A Murrey, Tucker L.
%A Hertel, Dirk
%A Nowak, Julian
%A Bruker, Ruth
%A Limböck, Thorsten
%A Neudörfl, Jörg
%A Rüth, Stephanie
%A Schelter, Jürgen
%A Olthof, Selina
%A Radulescu, Aurel
%A Moulé, Adam J.
%A Meerholz, Klaus
%T Investigation of Hierarchical Structure Formation in Merocyanine Photovoltaics
%J The journal of physical chemistry  / C
%V 124
%N 36
%@ 1932-7455
%C Washington, DC
%I Soc.
%M FZJ-2020-03106
%P 19457 - 19466
%D 2020
%X Merocyanines (MCs) are a versatile class of small-molecule dyes. Their optoelectronic properties are easily tunable by chemically controlling their donor–acceptor strength, and their structural properties can be tuned by simple side-chain substitution. This manuscript demonstrates a novel series of MCs featuring an indoline donor with varying hydrocarbon side-chain length (from 6 to 12 carbons) and a tert-butyl-thiazole acceptor, labeled InTBT. Bulk heterojunction organic photovoltaics are fabricated with a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) acceptor and characterized. Films composed of I8TBT:PCBM and I9TBT:PCBM produced the highest power conversion efficiency of 4.5%, which suggests that the morphology is optimized by controlling the side-chain length. Hierarchical structure formation in InTBT:PCBM films is studied using grazing incidence X-ray diffraction (GIXRD), small-angle neutron scattering (SANS), and atomic force microscopy (AFM). When mixed with PCBM, InTBTs with ≤8 side-chain carbons form pure crystalline domains, while InTBTs with ≥9 side-chain carbons mix well with PCBM. SANS demonstrates that increasing side-chain length increases the InTBT-rich domain size. In addition, a branched hexyl–dodecyl side-chain IHDTBT:PCBM film was studied and found to exhibit the worst-performance organic photovoltaic (OPV) device. The large-branched side chain inhibited mixing between IHDTBT and PCBM resulting in large segregated phases.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000571497000005
%R 10.1021/acs.jpcc.0c04988
%U https://juser.fz-juelich.de/record/884119