Origins of Charge Mobility Decreasing from Stretching-Releasing Cycles in Polymer Semiconductors

X Chen and K Li and BZ Min and ZB Li and L Duan and HY Li and SZ Li, MACROMOLECULES, 56, 7078-7085 (2023).

DOI: 10.1021/acs.macromol.3c01071

Polymer semiconductors as a key component of electronicskin needto maintain the coexistence of stretchability and electrical functionalities.However, repeated stretching-compressing cycles inevitablylead to the charge mobilities decreasing and poor working performanceof polymer semiconductors. Here, a method combining molecular dynamics(MD) simulations and charge transport theory was developed to obtainthe morphology-mobility relationship of amorphous poly(3-hexylthiophene)(P3HT). The simulation results show that the hole mobility decreasesby 6% along the strain direction after three stretching-compressingcycles with 80% strain. These results are due to the chain alignmentchange caused by the mechanical operations. The stretched P3HT materialpresents higher charge mobility due to its better chain alignment,while the compressed P3HT shows lower charge mobility because of thepoor chain alignment. Repeated stretching-compressing cycleslead to the chain alignment parameters decreasing along the deformationdirection with accumulation and saturation effects. The repeated cyclesalso result in the primitive path length decreasing, which indicatespolymer chain spatial distribution is more localized after repeateddeformations. Our findings provide microscale knowledge about thedependence of molecular morphology and charge mobility on stretching-compressingcycles, which can help to guide the design of polymer semiconductorswith higher charge mobility under repeated stretching-compressingcycles.

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