Electron Acceptors Based on Functionalizable Cyclopenta[hi]aceanthrylenes and Dicyclopenta[de,mn]tetracenes

Abstract

We report the synthesis and selective functionalization of two externally fused cyclopenta-fused polycyclic aromatic hydrocarbons (CP-PAHs) and demonstrate their electron accepting behavior. 2,7-Bis(trimethylsilyl)cyclopenta[hi]aceanthrylene (1) and 2,8-bis(trimethylsilyl)dicyclopenta[de,mn]tetracene (4) were prepared in a one-pot, palladium-catalyzed cross-coupling of (trimethylsilyl)acetylene and either 9,10-dibromoanthracene or 5,11-dibromotetracene, respectively. The trimethylsilyl groups were selectively converted into bromides via substitution with N-bromosuccinimide to create universal partners (2 and 6) for metal-catalyzed cross-coupling reactions. To demonstrate the utility of the halogenated CP-PAHs, we successfully employed a Sonogashira cross-coupling between the CP-PAHs and a phenylacetylene derivative. The resulting compounds (3 and 7) were found to be highly conjugated between the CP-PAH core and the substituents, as demonstrated by large bathochromic shifts in the absorption spectra as well as density functional theory calculations. Ethynylated CP-PAHs 3 and 7 were found to possess low optical bandgaps (1.52 and 1.51 eV, respectively) and displayed two reversible reductions. We further demonstrated the fullerene-like electron-accepting behavior of 3 through solution-phase fluorescence quenching of the prototypical electron donor, poly(3-hexylthiophene).

Tuning electron–hole distance of the excitons in organic molecules using functional groups

“…The current study suggests that the donor molecules MTPAo, MTPAcl, and MTPAc are all promising donor modula for organic photovoltaics, in addition to MTPA and MTPAa that were already being used. While MTPAo can be linked with an acceptor module covalently, MTPAcl and MTPAc, due to the terminal functional groups, could be used by forming a mixture with electron acceptors, such as the functionalizable dicyclopenta[de,mn]tetracenes [34]. We also note that the current proof-of-principles study allows us to identify the formation of CS excitons in organic molecules and to associate the non-radiative pathway to the annihilation of these CS excitons.…”

Charge Generation Pathways in Organic Solar Cells: Assessing the Contribution from the Electron Acceptor

“…127 These materials have recently been demonstrated to function as n-type semiconductors. 128 Figure 19a) to assess its IP and EA. The material exhibits two quasi-reversible reduction waves that were ascribed to the formation of two stabilized aromatic benzocyclipentadienyl anions.…”

Synthesis and properties of fully-conjugated indacenedithiophenes

“…1) and its derivatives have been utilized in device applications such as field effect transistors, photovoltaics, and light emitting diodes, these molecules are susceptible to oxidative and photolytic degradation; 2 therefore, alternative, acene-like topologies have been explored. 3–6 One of the initial substitutes for pentacene was structurally analogous anthradithiophene (ADT, 2 ), as inclusion of heterocycles allows for tuning of physical and electronic properties. 7 Thieno-fusion as part of the acene skeleton is a particularly attractive option for a number of reasons including high electron mobilities, increased stability, and ease of functionalization.…”