Two Regioisomeric π-Conjugated Small Molecules

Synthesis, Photophysical, Packing, and Optoelectronic Properties

Yuxiang Li, Dae Hee Lee, Joungphil Lee, Thanh Luan Nguyen, Sungu Hwang, Moon Jeong Park, Dong Hoon Choi, Han Young Woo

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Two regioisomeric D1-A-D-A-D1 type π-conjugated molecules (1,4-bis{5-[4-(5-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]­thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene (Prox-FBT) and 1,4-bis{5-[4-(6-fluoro-7-(5-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole)]­thiophen-2-yl}-2,5-bis(hexyldecyloxy)benzene (Dis-FBT)) are synthesized, by controlling the fluorine topology to be proximal or distal relative to the central core. The different F geometries are confirmed by the 1H–1H nuclear Overhauer effect spectroscopy (NOESY). Clearly different optical, electrochemical, and thermal transition behaviors are obtained, i.e., stronger absorption, deeper valance band (by ≈0.2 eV), and higher melting/recrystallization temperatures (by 7–20 °C) are observed for Dis-FBT. The different intermolecular packing and unit cell structures are also calculated for the two regioisomers, based on the powder X-ray diffraction and 2D grazing-incidence wide-angle X-ray diffraction measurements. A tighter π–π packing with a preferential monoclinic face-on orientation is extracted for Dis-FBT, compared to Prox-FBT with bimodal orientations. Different topological structures significantly affect the electrical and photovoltaic properties, where Prox-FBT shows higher parallel hole mobility (2.3 × 10−3 cm2 V−1 s−1), but Dis-FBT demonstrates higher power conversion efficiency (5.47%) with a larger open-circuit voltage of 0.95 V (vs 0.79 V for Prox-FBT). The findings suggest that small changes in the topological geometry can affect the electronic structure as well as self-assembly behaviors, which can possibly be utilized for fine-adjusting the electrical properties and further optimization of optoelectronic devices.

Original languageEnglish
Article number1701942
JournalAdvanced Functional Materials
Volume27
Issue number33
DOIs
Publication statusPublished - 2017 Sep 6

Fingerprint

Naproxen
Optoelectronic devices
Benzene
Thiadiazoles
Molecules
Hole mobility
Geometry
Open circuit voltage
synthesis
electrical properties
Fluorine
benzene
X ray powder diffraction
Self assembly
Conversion efficiency
Electronic structure
molecules
Melting
Electric properties
Topology

Keywords

  • fluorine
  • optoelectronics
  • packing
  • regioisomers
  • topology

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Condensed Matter Physics
  • Electrochemistry

Cite this

Two Regioisomeric π-Conjugated Small Molecules : Synthesis, Photophysical, Packing, and Optoelectronic Properties. / Li, Yuxiang; Lee, Dae Hee; Lee, Joungphil; Nguyen, Thanh Luan; Hwang, Sungu; Park, Moon Jeong; Choi, Dong Hoon; Woo, Han Young.

In: Advanced Functional Materials, Vol. 27, No. 33, 1701942, 06.09.2017.

Research output: Contribution to journalArticle

Li, Yuxiang ; Lee, Dae Hee ; Lee, Joungphil ; Nguyen, Thanh Luan ; Hwang, Sungu ; Park, Moon Jeong ; Choi, Dong Hoon ; Woo, Han Young. / Two Regioisomeric π-Conjugated Small Molecules : Synthesis, Photophysical, Packing, and Optoelectronic Properties. In: Advanced Functional Materials. 2017 ; Vol. 27, No. 33.
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