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Title: Properties of Poly- and Oligopentacenes Synthesized from Modular Building Blocks

Here, we describe a facile route to well-defined, solution-processable pentacene oligomers (2 to 7) and homopolymer using Suzuki–Miyaura cross-coupling reactions. This synthetic strategy leads to regioisomers, regiopure syn- and anti-trimers were also synthesized, revealing minimal changes in solution properties but significant changes in the solid state arising from differing levels of crystallinity. The materials were characterized by steady state absorption spectroscopy and cyclic voltammetry to study their electronic structure. The steady state absorption spectra exhibit a new high-energy transition in the oligomers, which intensifies as a function of oligomer length, thus increasing the range of absorption to include the entire visible spectrum. Density functional theory calculations indicate that the new peak results directly from the oligomerization. Solid state UV–vis suggests that while the monomer is amorphous, bricklayer packing in the higher oligomers significantly alters the solid state absorption relative to solution. The effect of oligomerization on packing was corroborated by GIWAXS analysis, which revealed crystalline domains in the oligomers. These domains, which are most evident in anti-trimer, become more pronounced upon thermal annealing. Photodegradation studies revealed considerable stability enhancement of oligomers toward oxygen and cycloaddition reactions relative to monomer. The synthesis and characterization of the first higher oligomers and homopolymermore » of pentacene should pave the way to applications in singlet fission, organic field-effect transistors, and organic photovoltaics.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [2] ;  [1]
  1. Columbia Univ., New York, NY (United States). Dept. of Chemistry
  2. Univ. of Houston, TX (United States). Dept. of Chemical and Biomolecular Engineering
  3. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
Publication Date:
Report Number(s):
BNL-112592-2016-JA
Journal ID: ISSN 0024-9297; R&D Project: 16063; 16058; KC0403020
Grant/Contract Number:
SC00112704; AC02-98CH10886; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 49; Journal Issue: 4; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Center for Functional Nanomaterials
OSTI Identifier:
1336126