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Kinetics and Mechanism of Poly(3-Hexylthiophene) Crystallization in Solution under Shear-flow



Ngoc A. Nguyen, Hao Shen, Yun Liu, Michael E. Mackay


The morphology of poly (3-hexylthiophene) (P3HT) in its liquid phase and its manipulation via flow-induced solution crystallization and its crystallization kinetics was studied to determine its mechanism. Shear-flow induced ordering of semi-conducting P3HT, which generates more perfect crystal structures than quiescent methods, is elucidated through using in-situ rheo-SANS and rheo-SALS and an Avrami analysis performed. Characteristic lengths of P3HT crystals were measured as a function of time, and 3-D networks of percolated P3HT fibril crystals were determined by measuring the fractal dimension, 2.6, through fitting rheo-SANS data with a power law function. Additionally, UV-Vis and DSC results revealed a process of P3HT crystal perfection determined by following the evolution of absorption peaks characteristic of pi-pi stacking at 600 nm and the melting peaks as they shifted and narrowed with respect to increasing shear time. The Avrami exponent, m, approached a maximum value of 2 indicating homogeneous nucleation of P3HT macromolecules that allowed 1-dimensional fibril crystal growing and limited by contact time between the P3HT molecules rather than the diffusion of P3HT chains that is attributed by the highly directional pi-pi stacking attractions of electron pi in the thiophene rings.


solar cell, small angle neutron scattering, Poly (3-hexylthiophene)


Nguyen, N. , Shen, H. , Liu, Y. and Mackay, M. (2020), Kinetics and Mechanism of Poly(3-Hexylthiophene) Crystallization in Solution under Shear-flow, Macromolecules, [online], (Accessed May 21, 2024)


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Created July 27, 2020, Updated October 12, 2021