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Estrada L.A.,Georgia Institute of Technology | Estrada L.A.,Center for Macromolecular Science and Engineering | Deininger J.J.,Georgia Institute of Technology | Deininger J.J.,Center for Macromolecular Science and Engineering | And 3 more authors.
ACS Macro Letters | Year: 2013

We report the use of direct (hetero)arylation polymerizations (DHAP) as a means of obtaining 3,4-propylenedioxythiophene-based conjugated polymers for use in electrochromics. This method offers a rapid route to achieving polymers in high yields with simplified purification procedures and low residual metal content, as determined by inductive coupled plasma-mass spectrometry (ICP-MS). The studied polymers possess comparable electrochromic properties to those previously reported by our group, implying that their switching ability from a colored to a transmissive state is independent of the residual metallic impurities. © 2013 American Chemical Society.

Graham K.R.,Center for Macromolecular Science and Engineering | Yang Y.,University of Florida | Sommer J.R.,Center for Macromolecular Science and Engineering | Shelton A.H.,Center for Macromolecular Science and Engineering | And 3 more authors.
Chemistry of Materials | Year: 2011

A family of π-extended platinum(II) porphyrins has been synthesized and incorporated into solution processed polymer light emitting diodes (PLEDs) and vapor deposited multilayer organic light emitting diodes (OLEDs), giving rise to devices with peak emission ranging from 771 to 1005 nm. The longest wavelength emitter, platinum(II)-5,10,15,20-(3,5-di-tert-butylphenyl)tetraanthroporphyrin (Pt-Ar 4TAP), shows an emission maximum at 1005 nm, an external quantum efficiency (EQE) of 0.12%, and a maximum radiant emittance (R max) of 0.23 mW/cm 2 in single layer PLED architectures, which is enhanced to an EQE of 0.20% with an R max of 0.57 mW/cm 2 upon vapor deposition of an electron transport layer. In an effort to understand substituent effects and enhance the performance of π-extended Pt-porphyrins in PLEDs and OLEDs, a family of Pt-tetrabenzoporphyrins (Pt-TBPs) with varying functionality was investigated. The luminescent lifetimes of the Pt-TBPs in solution and in films were measured, and a strong correlation was demonstrated between the film lifetimes and the PLED and OLED efficiencies. An improvement in external quantum efficiency (EQE) from 2.07 to 2.49% for PLEDs and from 8.0 to 9.2% for OLEDs was observed between the less substituted Pt-tetraphenyltetrabenzoporphyrin and the more substituted Pt-5,10,15,20-(3,5- di-tert-butylphenyl)tetrabenzoporphyrin. The PLED EQEs were further enhanced to 3.02% with the disubstituted Pt-5,15-(3,5-di-tert-butylphenyl) tetrabenzoporphyrin; however, this increase was not observed for the OLEDs where an EQE of 7.8% was measured. © 2011 American Chemical Society.

Chen Z.,Center for Macromolecular Science and Engineering | Hsu H.-Y.,Center for Macromolecular Science and Engineering | Arca M.,University of Florida | Schanze K.S.,Center for Macromolecular Science and Engineering
Journal of Physical Chemistry B | Year: 2015

Light harvesting and triplet energy transport is investigated in chromophore-functionalized polystyrene polymers featuring light harvesting and energy acceptor chromophores (traps) at varying loading. The series of precision polymers was constructed via reversible addition-fragmentation transfer polymerization and functionalized with platinum acetylide triplet chromophores by using an azide-alkyne "click" reaction. The polymers have narrow polydispersity and degree of polymerization ∼60. The chromophores have the general structure, trans-[-R-C6H4-C=C-Pt(PBu3)2-C=C-Ar], where R is the attachment point to the polystyrene backbone and Ar is either-C6H4-C=C-Ph or-pyrenyl (PE2-Pt and Py-Pt, respectively, with triplet energies of 2.35 and 1.88 eV). The polychromophores contain mainly the high-energy PE2-Pt units (light absorber and energy donor), with randomly distributed Py-Pt units (3-20% loading, energy acceptor). Photophysical methods are used to study the dynamics and efficiency of energy transport from the PE2-Pt to Py-Pt units in the polychromophores. The energy transfer efficiency is >90% for copolymers that contain 5% of the Py-Pt acceptor units. Time-resolved phosphorescence measurements combined with Monte Carlo exciton dynamics simulations suggest that the mechanism of exciton transport is exchange energy transfer hopping between PE2-Pt units. © 2014 American Chemical Society.

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