TY - JOUR
T1 - Optical spectra and exchange-correlation effects in molecular crystals
AU - Sai, Na
AU - Tiago, Murilo L.
AU - Chelikowsky, James R.
AU - Reboredo, Fernando A.
PY - 2008/4/30
Y1 - 2008/4/30
N2 - We report the first-principles GW -Bethe-Salpeter equation and quantum Monte Carlo calculations of the optical and electronic properties of molecular and crystalline rubrene (C42 H28). Many-body effects dominate the optical spectrum and quasiparticle gap of molecular crystals. We interpret the observed yellow-green photoluminescence in rubrene microcrystals as a result of the formation of intermolecular, charge-transfer, spin-singlet excitons. In contrast, spin-triplet excitons are localized and intramolecular with a predicted phosphorescence at the red end of the optical spectrum. We find that the exchange energy plays a fundamental role in raising the energy of intramolecular spin-singlet excitons above the intermolecular ones. Exciton binding energies are predicted to be around 0.5 eV (spin singlet) to 1 eV (spin triplet). The calculated electronic gap is 2.8 eV. The theoretical absorption spectrum agrees very well with recent ellipsometry data.
AB - We report the first-principles GW -Bethe-Salpeter equation and quantum Monte Carlo calculations of the optical and electronic properties of molecular and crystalline rubrene (C42 H28). Many-body effects dominate the optical spectrum and quasiparticle gap of molecular crystals. We interpret the observed yellow-green photoluminescence in rubrene microcrystals as a result of the formation of intermolecular, charge-transfer, spin-singlet excitons. In contrast, spin-triplet excitons are localized and intramolecular with a predicted phosphorescence at the red end of the optical spectrum. We find that the exchange energy plays a fundamental role in raising the energy of intramolecular spin-singlet excitons above the intermolecular ones. Exciton binding energies are predicted to be around 0.5 eV (spin singlet) to 1 eV (spin triplet). The calculated electronic gap is 2.8 eV. The theoretical absorption spectrum agrees very well with recent ellipsometry data.
UR - http://www.scopus.com/inward/record.url?scp=43049103439&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.77.161306
DO - 10.1103/PhysRevB.77.161306
M3 - Article
AN - SCOPUS:43049103439
SN - 1098-0121
VL - 77
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 16
M1 - 161306
ER -