Nearly 50-50 Face-on to Edge-on Crystallites in Regioisomeric Polymers Based on n-Type Thienylvinyl-1,1-dicyanomethylene-3-indanone for High Electron Mobility

Seunglok Lee; Sangwook Lee; Seonghun Jeong; Jaeyong Ahn; Sangjin Yang; Seokhwan Jeong; Yongjoon Cho; Joon Hak Oh; Changduk Yang

doi:10.1021/acsami.5c05769

Nearly 50-50 Face-on to Edge-on Crystallites in Regioisomeric Polymers Based on n-Type Thienylvinyl-1,1-dicyanomethylene-3-indanone for High Electron Mobility

ACS Appl Mater Interfaces. 2025 Jul 9;17(27):39366-39374. doi: 10.1021/acsami.5c05769. Epub 2025 Jun 26.

Authors

Seunglok Lee¹, Sangwook Lee², Seonghun Jeong¹, Jaeyong Ahn², Sangjin Yang¹, Seokhwan Jeong¹, Yongjoon Cho^{1

3}, Joon Hak Oh², Changduk Yang^{1

4}

Affiliations

¹ School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan 44919, South Korea.
² School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea.
³ Department of Chemistry, the Materials Research Center, Trienens Institute for Sustainability and Energy, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
⁴ Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulju-gun, Ulsan 44919, South Korea.

PMID: 40574321
DOI: 10.1021/acsami.5c05769

Abstract

To better understand how backbone regioregularity at the molecular level influences the bulk properties of conjugated polymers, we investigated the optical and electrochemical properties, energetics, microstructure, and charge transport characteristics of newly synthesized regioisomeric polymers. These include a regiorandom polymer (PTIC) and two regioregular analogs (PTIC-γ and PTIC-δ). All these polymers exhibit a broad infrared absorption band covering from 300 to 1000 nm, a narrow band gap of 1.25 eV, and a low-lying lowest unoccupied molecular orbital deeper than 3.88 eV. PTIC-γ features weaker chain-to-chain packing owing to its U-shape backbone, whereas PTIC and PTIC-δ present strong aggregation with their wave-like backbone shapes. Initially, all pristine polymer films reveal a bimodal texture dominated by a preferential face-on orientation. Following thermal annealing, the crystallites reorient further into a nearly exclusive face-on packing for PTIC-γ and PTIC-δ films, whereas PTIC films maintain a roughly 50-50 face-on to edge-on orientation ratio. As a result, the best electron mobility, reaching 1.43 × 10^-1 cm² V^-1 s^-1, is achieved from the annealed PTIC film owing to the construction of a continuous 3D charge-transport pathway.

Keywords: crystallite orientation; diketopyrrolopyrrole; electron mobility; n-type organic field effect transistors; polymer conformation; regioregularity.