Design and synthesis of light-harvesting rods for intrinsic rectification of the migration of excited-state energy and ground-state holesElectronic supplementary information (ESI) available: 1H and 13C NMR spectra for all new porphyrin precursors; 1H NMR and LD-MS spectra for all new porphyrins and porphyrin arrays (LD-MS only for deprotected arrays 12′ and 14′, and pentad 18); analytical SEC data for all porphyrin arrays. See http://www.rsc.org/suppdata/jm/b1/b108168c/
作者:Robert S. Loewe、Robin K. Lammi、James R. Diers、Christine Kirmaier、David F. Bocian、Dewey Holten、Jonathan S. Lindsey
DOI:10.1039/b108168c
日期:2002.4.17
We present the design of molecular materials for ultimate use in solid-state solar cells. The molecular materials are semi-rigid oligomeric rods of defined length with metalloporphyrins in the backbone and a carboxy group at one end for attachment to a surface. The rods are designed to absorb visible light, and then undergo excited-state energy transfer and ground-state hole transfer in opposite directions along the length of the rod. The rational synthesis of the multiporphyrin arrays relies on joining porphyrin building blocks in an efficient and controlled manner. Several porphyrin building blocks have been synthesized that bear bromophenyl, iodophenyl, trimethylsilylethynylphenyl and/or ethynylphenyl substituents for use in a copper-free Sonogashira reaction using Pd2(dba)3 and P(o-tol)3. Competition experiments performed on equimolar quantities of an iodo-porphyrin and a bromo-porphyrin with an ethynyl-porphyrin
show iodo + ethyne coupling with a low amount (35 °C) or undetectable amount (22 °C) of bromo + ethyne coupling. Efficient coupling of bromo-porphyrins with ethynyl-porphyrins was achieved using the same copper-free Sonogashira reaction conditions at higher temperature (50 °C or 80 °C). These findings allow successive coupling reactions to be achieved using substrates bearing iodo and bromo synthetic handles. Thus, a porphyrin-based tetrad (or pentad) was synthesized with a final convergent coupling of a bromo-substituted dyad (or triad) and an ethynyl-substituted dyad. A porphyrin triad was prepared by sequential iodo + ethyne coupling reactions. The triad, tetrad, and pentad each are comprised of a terminal magnesium porphyrin bearing one carboxy group (for surface attachment) and two pentafluorophenyl groups; the remaining porphyrins in each array are present as the zinc chelate. Electrochemical
characterization of benchmark porphyrins indicates the presence of the desired electrochemical gradient for hole hopping in the arrays. Static absorption data indicate that the arrays are weakly coupled, while static fluorescence data indicate that the excited-state energy flows in high yield to the terminal magnesium porphyrin. Time-resolved spectroscopic analysis leads to rate constants in THF of (9 ps)−1, (15 ps)−1, and (30 ps)−1 for ZnMg dyad 20, Zn2Mg triad 13, and Zn3Mg tetrad 15, respectively, and quantum efficiencies ≥99% for energy flow to the magnesium porphyrin in each case. These design and synthesis strategies should be useful for the construction of materials for molecular-based solar cells.
Molecular Engineering of Boryl Oxasmaragdyrins through Peripheral Modification: Structure-Efficiency Relationship
作者:Sandeep B. Mane、Chen-Hsiung Hung
DOI:10.1002/chem.201405856
日期:2015.3.16
Expanded porphyrins with the absorption profile down to the infrared region through increased π‐conjugation are suitable candidates for a low energy sensitizer. Oxasmaragdyrin boron complexes, a class of aromatic‐core‐modified expanded porphyrin with 22 π‐electrons, have been recently utilized as an efficient low energy sensitizer in dye‐sensitized solar cells. In this paper, we have prepared a series
Two Si–porphyrin hybrid monolayers showed room temperature negative differential resistance (NDR) property. The monolayer with a fluorophenyl porphyrin moiety showed a better peak-to-valley ratio due to compact packing.
BODIPY-based conjugated polymers for broadband light sensing and harvesting applications
作者:Diego Cortizo-Lacalle、Calvyn T. Howells、Salvatore Gambino、Filipe Vilela、Zuzana Vobecka、Neil J. Findlay、Anto R. Inigo、Stuart A. J. Thomson、Peter J. Skabara、Ifor D. W. Samuel
DOI:10.1039/c2jm32374e
日期:——
The synthesis of novel low band-gap polymers has significantly improved light sensing and harvesting in polymer–fullerene devices. Here the synthesis of two low band-gap polymers based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene core (BODIPY), and either bis(3,4-ethylenedioxythiophene) (bis-EDOT) or its all-sulfur analogue bis(3,4-ethylenedithiathiophene) (bis-EDTT) are described. The polymers demonstrate ambipolar charge transport and are shown to be suitable for broadband light sensing and solar energy harvesting in solution-processable polymer–fullerene devices.