Unraveling the Molar Mass Dependence of Shearing-Induced Aggregation Structure of a High-Mobility Polymer Semiconductor.
basic_science · Level V
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- Record sourced from PubMed, PMID 34850998.
- Also identified by DOI 10.1002/adma.202108255.
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Abstract
Aggregation-structure formation of conjugated polymers is a fundamental problem in the field of organic electronics and remains poorly understood. Herein, the molar mass dependence of the aggregation structure of a high-mobility conjugated copolymer (TDPP-Se) comprising thiophene-flanked diketopyrrolopyrrole and selenophene is thoroughly shown. Five batches of TDPP-Se are prepared with the number-average molecular weights (M<sub>n</sub> ) varied greatly from 21 to 135 kg mol<sup>-1</sup> . Small-angle neutron scattering and transmission electron microscopy are combined to probe the solution structure of these polymers, consistently using a deuterated solvent. All the polymers adopt 1D rod-like aggregation structures and the radius of the 1D rods is not sensitive to the M<sub>n</sub> , while the length increases monotonically with M<sub>n</sub> . By utilizing the ordered packing of the aggregated structure in solution, a highly aligned and ordered film is prepared and, thereafter, a reliable hole mobility of 13.8 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> is realized in organic thin-film transistors with the moderate M<sub>n</sub> batch via bar coating. The hole mobility is among the highest values reported for diketopyrrolopyrrole-based polymers. This work paves the way to visualize the real aggregated structure of polymer semiconductors in solution and sheds light on the microstructure control of high-performance electronic devices.