Anticipating acene-based chromophore spectra with molecular orbital arguments

Abstract

Recent synthetic studies on the organic molecules tetracene and pentacene have found certain dimers and oligomers to exhibit an intense absorption in the visible region of the spectrum which is not present in the monomer or many previously-studied dimers. In this article we combine experimental synthesis with electronic structure theory and spectral computation to show that this absorption arises from an otherwise dark charge-transfer excitation 'borrowing intensity' from an intense UV excitation. Further, by characterizing the role of relevant monomer molecular orbitals, we arrive at a design principle that allows us to predict the presence or absence of an additional absorption based on the bonding geometry of the dimer. We find this rule correctly explains the spectra of a wide range of acene derivatives and solves an unexplained structure-spectrum phenomenon first observed seventy years ago. These results pave the way for the design of highly absorbent chromophores with applications ranging from photovoltaics to liquid crystals.

arXiv comment29 pages, 63 pages with SI, 5 figures

References in corpus (4)

• Dependence of Single Molecule Junction Conductance on Molecular Conformation
• A large-scale correlated study of linear optical absorption and low-lying excited states of polyacenes: Pariser-Parr-Pople Hamiltonian
• Theory of interfacial charge-transfer complex photophysics in $\pi$-conjugated polymer-fullerene blends
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Cited by in corpus (4)

• Alternant Hydrocarbon Diradicals as Optically Addressable Molecular Qubits
• Inverse molecular design from first principles: tailoring organic chromophore spectra for optoelectronic applications
• Heterogeneous Singlet Fission in a Covalently Linked Pentacene Dimer
• ExROPPP: Fast, Accurate and Spin-Pure Calculation of the Electronically Excited States of Organic Hydrocarbon Radicals