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

16 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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