Microstructural Variation upon Introducing Di([2,2′-bithiophen]-5-yl)pyrenes into a Naphthalene Diimide-Based Polymer
Journal
ACS Omega
Journal Volume
10
Journal Issue
45
Start Page
55105
End Page
55114
ISSN
24701343
Date Issued
2025-11-18
Author(s)
Abstract
Four pyrene-based conjugated molecules─1,6-bis(bithiophene)pyrene (A), 1,6-bis[5-octyl-(2,2′-bithiophen)-5′-yl]pyrene (B), 2,7-bis[5-octyl-(2,2′-bithiophen)-5′-yl]pyrene (C), and 4,9-bis[5-octyl-(2,2′-bithiophen)-5′-yl]pyrene (D)─have been designed, synthesized, and blended with poly[[1,2,3,6,7,8-hexahydro-2,7-bis(2-octyldodecyl)-1,3,6,8-dioxobenzo[lmn][3,8]phenanthroline-4,9-diyl][2,2′-bithiophene]-5,5′-diyl] (P(NDI2OD-T2, P). The structural difference between A and B lies in the presence of an alkyl substituent, while B, C, and D are regioisomers. The effects of the alkyl substituent and regioisomerism on the microstructure of P have been investigated. Differential scanning calorimetry and1H NMR spectroscopy suggest that alkyl substitution may not play a significant role in determining the crystallization and aggregation of P. In contrast, regioisomerism significantly influences these properties. Grazing-incidence X-ray scattering indicates that while the alkyl substituent affects lamellar stacking, regioisomerism plays a crucial role in shaping the polymer’s microstructure. The introduction of pyrene enhances polymer backbone rigidification, likely due to the establishment of naphthalene diimide–pyrene interactions, as supported by density functional theory calculations. Organic field-effect transistor measurements reveal that the blends can exhibit higher electron mobility (μe) than P. Linear regression analysis suggests that the crystallization of P is correlated with μe. Lastly, the current blending approach is compared with the previous incorporation approach, highlighting the role of molecular degrees of freedom in contributing to the observed differences.
Publisher
American Chemical Society
Type
journal article