Synthesis and characterization of highly soluble phenanthro[1,10,9,8-c,d,e,f,g]carbazole-based copolymer: Effects of thermal treatment on crystalline order and charge carrier mobility

Abstract Herein, we report the synthesis and characterization of four regioregular, well-defined donor–acceptor polymers (P1, P2, P3, and P4), comprising different compositions of axisymmetric cyclopentadithiophene (CDT) and centrosymmetric indacenodithiophene (IDT) donors in conjugation with the asymmetric 5-fluoro-2,1,3-benzothiadiazole acceptor that is precisely oriented in the regular pattern along the backbone. Morphological analyses of the above polymer series show that exclusive CDT donor-containing P1 is semicrystalline, whereas the others (IDT donor-containing ones) are near-amorphous in nature. Comparatively, IDT donor-containing polymers have superior hole mobilities; in particular, exclusive IDT donor-containing polymer P4 offers an ultra-high mobility of 13.82 cm2 V− 1 s− 1 at a channel length of 200 µm, which is comparable to the recently reported values for state-of-the-art semicrystalline semiconductors. In addition, the near-amorphous characteristics render the IDT donor-containing polymer films highly ductile and stretchable. Such superior features, which are associated with excellent charge transport and ductility, demonstrate a promising possibility for application in viable stretchable electronics.

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The Influence of Nitrogen Position on Charge Carrier Mobility in Enantiopure Aza[6]helicene Crystals

10.26434/chemrxiv.7458719.v1 ◽

2018 ◽

Author(s):

Francesco Salerno ◽

Beth Rice ◽

Julia Schmidt ◽

Matthew J. Fuchter ◽

Jenny Nelson ◽

...

Keyword(s):

Solid State ◽

Charge Carrier ◽

Carrier Mobility ◽

Chemical Structure ◽

Crystal Packing ◽

Charge Carrier Mobility ◽

Individual Factor ◽

Charge Mobility ◽

Order Of Magnitude ◽

Small Change

<p>The properties of an organic semiconductor are dependent on both the chemical structure of the molecule involved, and how it is arranged in the solid-state. It is challenging to extract the influence of each individual factor, as small changes in the molecular structure often dramatically change the crystal packing and hence solid-state structure. Here, we use calculations to explore the influence of the nitrogen position on the charge mobility of a chiral organic molecule when the crystal packing is kept constant. The transfer integrals for a series of enantiopure aza[6]helicene crystals sharing the same packing were analysed in order to identify the best supramolecular motifs to promote charge carrier mobility. The regioisomers considered differ only in the positioning of the nitrogen atom in the aromatic scaffold. The simulations showed that even this small change in the chemical structure has a strong effect on the charge transport in the crystal, leading to differences in charge mobility of up to one order of magnitude. Some aza[6]helicene isomers that were packed interlocked with each other showed high HOMO-HOMO integrals (up to 70 meV), whilst molecules arranged with translational symmetry generally afforded the highest LUMO-LUMO integrals (40 - 70 meV). As many of the results are not intuitively obvious, a computational approach provides additional insight into the design of new semiconducting organic materials.</p>

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