The physics of aggregates of polar and polarizable donor–acceptor dyes is discussed, extending a previous model to account for the coupling of electronic and vibrational degrees of freedom. Fully exploiting transla- tional symmetry, exact absorption and fluorescence spectra are calculated for aggregates with up to 6 mole- cules. A two-step procedure is presented: in the first step, a mean-field solution of the problem is proposed to define the excitonic basis via a rotation of the electronic basis. The rotation is also accompanied by a Lang–Firsov transformation of the vibrational basis. In the second step, the aggregate Hamiltonian, written on the exciton basis, is diagonalized towards exact results. The procedure leads to a reduction of the dimension of the problem, since, at least for weak coupling, only states with up to 3 excitons are needed to obtain reliable results. More interestingly, the mean-field solution represents the proper reference state to discuss excitonic and ultraexcitonic effects. The emerging picture demonstrates that the exciton model offers a reliable description of aggregates of polar and polarizable dyes in the weak coupling regime, while ultraexcitonic effects are important in the medium-strong coupling regimes, and particularly so for J-aggregates where ultraexcitonic effects show up most clearly with multistability and multiexciton generation.

Aggregates of polar dyes: beyond the exciton model / Anzola, Mattia; Painelli, Anna. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 23:(2021), pp. 8282-8291. [10.1039/D1CP00335F]

Aggregates of polar dyes: beyond the exciton model

Anzola, Mattia;Painelli, Anna
2021-01-01

Abstract

The physics of aggregates of polar and polarizable donor–acceptor dyes is discussed, extending a previous model to account for the coupling of electronic and vibrational degrees of freedom. Fully exploiting transla- tional symmetry, exact absorption and fluorescence spectra are calculated for aggregates with up to 6 mole- cules. A two-step procedure is presented: in the first step, a mean-field solution of the problem is proposed to define the excitonic basis via a rotation of the electronic basis. The rotation is also accompanied by a Lang–Firsov transformation of the vibrational basis. In the second step, the aggregate Hamiltonian, written on the exciton basis, is diagonalized towards exact results. The procedure leads to a reduction of the dimension of the problem, since, at least for weak coupling, only states with up to 3 excitons are needed to obtain reliable results. More interestingly, the mean-field solution represents the proper reference state to discuss excitonic and ultraexcitonic effects. The emerging picture demonstrates that the exciton model offers a reliable description of aggregates of polar and polarizable dyes in the weak coupling regime, while ultraexcitonic effects are important in the medium-strong coupling regimes, and particularly so for J-aggregates where ultraexcitonic effects show up most clearly with multistability and multiexciton generation.
2021
Aggregates of polar dyes: beyond the exciton model / Anzola, Mattia; Painelli, Anna. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 23:(2021), pp. 8282-8291. [10.1039/D1CP00335F]
File in questo prodotto:
File Dimensione Formato  
polar-aggregates-PCCPaccepted.pdf

accesso aperto

Descrizione: main text
Tipologia: Documento in Post-print
Licenza: Creative commons
Dimensione 3.15 MB
Formato Adobe PDF
3.15 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2891700
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 12
  • ???jsp.display-item.citation.isi??? 12
social impact