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Side-chain sequence enabled regioisomeric acceptors, bearing different side-chain sequences on the same conjugated backbone, are herein reported. Two regioregular polymers PTBI-1 and PTBI-2 and one regiorandom polymer PTBI-3 were synthesized from these two regioisomeric acceptors for a comparative study. UV–vis–NIR absorption spectroscopy and electrochemical study confirmed similar frontier molecular orbital levels of the three polymers in their solid state. More intriguingly, absorption profiles suggest that the sequence of side chains greatly governs the aggregation behaviors. Furthermore, the PTBI-2 film shows larger ordered domains than PTBI-1 and PTBI-3 films, as supported by AFM and GIWAXS measurements. As a result, PTBI-2-based FET devices achieved an average hole mobility of 1.37 cm2 V–1 s–1, much higher than the two polymers with other side-chain sequences. The regiorandom PTBI-3 exhibited the lowest average hole mobility of 0.27 cm2 V–1 s–1. This study highlights the significant impact of side-chain sequence regioisomerism on aggregation behaviors, morphologies, and subsequently charge transport properties of donor–acceptor type conjugated polymers.
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Tying Together Multiscale Calculations for Charge Transport in P3HT: Structural Descriptors, Morphology, and Tie-Chains
Evaluating new, promising organic molecules to make next-generation organic optoelectronic devices necessitates the evaluation of charge carrier transport performance through the semi-conducting medium. In this work, we utilize quantum chemical calculations (QCC) and kinetic Monte Carlo (KMC) simulations to predict the zero-field hole mobilities of ∼100 morphologies of the benchmark polymer poly(3-hexylthiophene), with varying simulation volume, structural order, and chain-length polydispersity. Morphologies with monodisperse chains were generated previously using an optimized molecular dynamics force-field and represent a spectrum of nanostructured order. We discover that a combined consideration of backbone clustering and system-wide disorder arising from side-chain conformations are correlated with hole mobility. Furthermore, we show that strongly interconnected thiophene backbones are required for efficient charge transport. This definitively shows the role “tie-chains” play in enabling mobile charges in P3HT. By marrying QCC and KMC over multiple length- and time-scales, we demonstrate that it is now possible to routinely probe the relationship between molecular nanostructure and device performance.
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- PAR ID:
- 10084743
- Date Published:
- Journal Name:
- Polymers
- Volume:
- 10
- Issue:
- 12
- ISSN:
- 2073-4360
- Page Range / eLocation ID:
- 1358
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/polym10121358
