On the growth, structure and dynamics of P3EHT crystals

Author(s)

Faria, Gregorio C. ^[1] ; Duong, Duc T. ^[2] ; da Cunha, Giovanni Paro ^[1] ; Selter, Philipp ^[3] ; Strasso, Lasse Arnt ^{[4, 5]} ; Davidson, Emily C. ^[6] ; Segalman, Rachel A. ^{[6, 7]} ; Hansen, Michael Ryan ^[3] ; deAzevedo, Eduardo Ribeiro ^[1] ; Salleo, Alberto ^[2]

Affiliation

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, CP 369, BR-13660970 Sao Carlos, SP - Brazil

^[2] Stanford Univ, Dept Mat Sci & Engn, Stanford, CA 94305 - USA

^[3] Westfalische Wilhelms Univ Munster, Inst Phys Chem, Corrensstr 28-30, D-48149 Munster - Germany

^[4] Aarhus Univ, Interdisciplinary Nanosci Ctr, Gustav Wieds Vej 14, DK-8000 Aarhus C - Denmark

^[5] Aarhus Univ, Sch Engn Chem & Biotechnol Engn, Hangovej 2, DK-8200 Aarhus N - Denmark

^[6] Univ Calif Santa Barbara, Dept Chem Engn, Santa Barbara, CA 93106 - USA

^[7] Univ Calif Santa Barbara, Mat Dept, Santa Barbara, CA 93106 - USA

• Document type: Journal article
• Source: JOURNAL OF MATERIALS CHEMISTRY C; v. 8, n. 24, p. 8155-8170, JUN 28 2020.
• Web of Science Citations: 3

Abstract

We employ X-ray diffraction, NMR and UV-vis spectroscopy techniques to shed light on the structure, molecular mobility and crystallization of a prototypical semiconducting polymer poly(3-(2 `-ethylhexyl)thiophene) (P3EHT). Grazing-incidence X-ray diffraction (GIXD) and high-field(1)H-H-1 double-quantum NMR reveal a tilt of the thiophene rings along the main chains, while high resolution(13)C solid-state NMR methods show the presence of highly mobile side-chains. Taken together, the data reveal a high amount of free volume between adjacent chains in the crystalline phase, most likely owing to the additional steric hindrance from the branched ethyl group of the hexyl side chains. Additionally, the aforementioned methods allow us to confirm that crystallization in P3EHT occurs in a one-dimensional fashion along the polymer backbone. An extended model based on the Avrami principles is used to fit the experimental results to extract key parameters, such as nucleation rate and density, that govern these crystallization processes. The results show significantly reduced rates of crystallization in thin P3EHT thin films due to polymer chain confinement effects. (AU)

• FAPESP's process: 13/21034-0 - Organic bioelectronics: from materials characterization to devices development
• Grantee: Gregório Couto Faria
• Support Opportunities: Scholarships abroad - Research