TY  - JOUR
AU  - Murrey, Tucker L.
AU  - Hertel, Dirk
AU  - Nowak, Julian
AU  - Bruker, Ruth
AU  - Limböck, Thorsten
AU  - Neudörfl, Jörg
AU  - Rüth, Stephanie
AU  - Schelter, Jürgen
AU  - Olthof, Selina
AU  - Radulescu, Aurel
AU  - Moulé, Adam J.
AU  - Meerholz, Klaus
TI  - Investigation of Hierarchical Structure Formation in Merocyanine Photovoltaics
JO  - The journal of physical chemistry  / C
VL  - 124
IS  - 36
SN  - 1932-7455
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2020-03106
SP  - 19457 - 19466
PY  - 2020
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000571497000005
DO  - DOI:10.1021/acs.jpcc.0c04988
UR  - https://juser.fz-juelich.de/record/884119
ER  -