TY  - JOUR
A1  - Samson, Stephanie
A1  - Rech, Jeromy
A1  - Perdigon-Toro, Lorena
A1  - Peng, Zhengxing
A1  - Shoaee, Safa
A1  - Ade, Harald
A1  - Neher, Dieter
A1  - Stolterfoht, Martin
A1  - You, Wei
T1  - Organic solar cells with large insensitivity to donor polymer molar mass across all acceptor classes
JF  - ACS applied polymer materials
N2  - Donor polymer number-average molar mass (M-n) has long been known to influence organic photovoltaic (OPV) performance via changes in both the polymer properties and the resulting bulk heterojunction morphology. The exact nature of these M-n effects varies from system to system, although there is generally some intermediate M-n that results in optimal performance. Interestingly, our earlier work with the difluorobenzotriazole (FTAZ)-based donor polymer, paired with either N2200 (polymer acceptor) or PC61BM (fullerene acceptor), PcBm demonstrated <10% variation in power conversion efficiency and a consistent morphology over a large span of M-n (30 kg/mol to over 100 kg/mol). Would such insensitivity to polymer M-n still hold true when prevailing small molecular acceptors were used with FTAZ? To answer this question, we explored the impact of FTAZ on OPVs with ITIC, a high-performance small-molecule fused-ring electron acceptor (FREA). By probing the photovoltaic characteristics of the resulting OPVs, we show that a similar FTAZ mn insensitivity is also found in the FTAZ:ITIC system. This study highlights a single-donor polymer which, when paired with an archetypal fullerene, polymer, and FREA, results in systems that are largely insensitive to donor M. Our results may have implications in polymer batch-to-batch reproducibility, in particular, relaxing the need for tight M-n control during synthesis.
KW  - polymer solar cells
KW  - conjugated polymers
KW  - fullerenes
KW  - fluorination
KW  - molecular weight
KW  - non-fullerene acceptors
KW  - power conversion efficiency
Y1  - 2020
U6  - https://doi.org/10.1021/acsapm.0c01041
SN  - 2637-6105
VL  - 2
IS  - 11
SP  - 5300
EP  - 5308
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tan, Li
A1  - Liu, Bing
A1  - Siemensmeyer, Konrad
A1  - Glebe, Ulrich
A1  - Böker, Alexander
T1  - Synthesis of Polystyrene-Coated Superparamagnetic and Ferromagnetic Cobalt Nanoparticles
JF  - Polymers
N2  - Polystyrene-coated cobalt nanoparticles (NPs) were synthesized through a dual-stage thermolysis of cobalt carbonyl (Co-2(CO)(8)). The amine end-functionalized polystyrene surfactants with varying molecular weight were prepared via atom-transfer radical polymerization technique. By changing the concentration of these polymeric surfactants, Co NPs with different size, size distribution, and magnetic properties were obtained. Transmission electron microscopy characterization showed that the size of Co NPs stabilized with lower molecular weight polystyrene surfactants (M-n = 2300 g/mol) varied from 12-22 nm, while the size of Co NPs coated with polystyrene of middle (M-n = 4500 g/mol) and higher molecular weight (M-n = 10,500 g/mol) showed little change around 20 nm. Magnetic measurements revealed that the small cobalt particles were superparamagnetic, while larger particles were ferromagnetic and self-assembled into 1-D chain structures. Thermogravimetric analysis revealed that the grafting density of polystyrene with lower molecular weight is high. To the best of our knowledge, this is the first study to obtain both superparamagnetic and ferromagnetic Co NPs by changing the molecular weight and concentration of polystyrene through the dual-stage decomposition method.
KW  - cobalt nanoparticles
KW  - polystyrene
KW  - superparamagnetic
KW  - ferromagnetic
KW  - molecular weight
Y1  - 2018
U6  - https://doi.org/10.3390/polym10101053
SN  - 2073-4360
VL  - 10
IS  - 10
PB  - MDPI
CY  - Basel
ER  -