Self-seeded growth of poly(3-hexylthiophene) (P3HT) nanofibrils by a cycle of cooling and heating in solutions

Jin Young Oh, Minkwan Shin, Tae Il Lee, Woo Soon Jang, Yuho Min, Jae Min Myoung, Hong Koo Baik, Unyong Jeong

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Abstract

In spite of the recent successes in transistors and solar cells utilizing poly(3-hexylthiophene) (P3HT) nanofibrils, systematic analysis on the growth kinetics has not been reported due to the lack of analytical tools. This study proposed a simple spectroscopic method to obtain the crystallinity of P3HT in solutions. On the basis of the analytical approach, we found that the crystallinity hysteresis upon temperature is a simple function of the solubility parameter difference (Δδ) between the P3HT and the solvents. When Δδ ≥ 0.7, a cooling (-20 °C)-and-heating (25 °C) process allowed the preparation of solutions including 1D crystal seeds dispersed in the solution. Simple coating of the seeded solutions completed the growth of the seeds into long nanofibrils at the early stage of the coating and thereby achieved almost 100% crystallinity in the resulting films without any postannealing process. The existence of PCBM for bulk-heterojunction (BHJ) solar cells did not affect the nucleation and growth of the nanofibrils during the cooling-and-heating process. The solar cells prepared from the solutions with Δδ ≥ 0.7 had solar conversion efficiencies higher than the conventional thermally annealed cells.

Original languageEnglish
Pages (from-to)7504-7513
Number of pages10
JournalMacromolecules
Volume45
Issue number18
DOIs
Publication statusPublished - 2012 Sep 25

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All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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