Optical absorption and photoluminescence in pristine and photopolymerized C60 solid films.
Optical absorption and photoluminescence in pristine and photopolymerized C60 solid films.
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DOI：
10.1103/physrevb.51.4547
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发表时间：
1995-02
期刊：
影响因子：
--
通讯作者：
Ying Wang;J. Holden;A. M. Rao;P. Eklund;U. Venkateswaran;D. Eastwood;R. Lidberg;G. Dresselhaus;M. Dresselhaus
中科院分区：
文献类型：
--
作者：
Ying Wang;J. Holden;A. M. Rao;P. Eklund;U. Venkateswaran;D. Eastwood;R. Lidberg;G. Dresselhaus;M. Dresselhaus
The optical absorption (OA) and photoluminescence (PL) spectra of pristine, oxygen-free ${\mathrm{C}}_{60}$ films in the vicinity of the absorption edge across the highest-occupied-molecular-orbital to lowest-unoccupied-molecular-orbital (HOMO-LUMO) gap are studied to elucidate the nature of these electronic states. Structures observed in both the OA and PL spectra are identified with Herzberg-Teller vibronic coupling of the respective singlet electronic states to intramolecular vibrational modes. Similarities and differences among the PL and OA spectra of ${\mathrm{C}}_{60}$ in solution, solid films, and single crystals are discussed. The larger linewidth of the ${\mathrm{C}}_{60}$ film spectra is attributed to the presence of defects, presumably associated with numerous grain boundaries. Finally, the OA and PL spectra of photopolymerized ${\mathrm{C}}_{60}$ solid films are presented. The features in both the OA and PL spectra are observed to broaden considerably. In addition, two of the OA bands blueshift slightly (400\char21{}800 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) and the PL features downshift by \ensuremath{\sim}330 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ upon polymerization. These results are consistent with the intermolecular oligomerization bond disorder and reduced symmetry of the ${\mathrm{C}}_{60}$ shell imposed by the covalent bonds between ${\mathrm{C}}_{60}$ molecules in the polymeric phase.
The optical absorption (OA) and photoluminescence (PL) spectra of pristine, oxygen-free ${\mathrm{C}}_{60}$ films in the vicinity of the absorption edge across the highest-occupied-molecular-orbital to lowest-unoccupied-molecular-orbital (HOMO-LUMO) gap are studied to elucidate the nature of these electronic states. Structures observed in both the OA and PL spectra are identified with Herzberg-Teller vibronic coupling of the respective singlet electronic states to intramolecular vibrational modes. Similarities and differences among the PL and OA spectra of ${\mathrm{C}}_{60}$ in solution, solid films, and single crystals are discussed. The larger linewidth of the ${\mathrm{C}}_{60}$ film spectra is attributed to the presence of defects, presumably associated with numerous grain boundaries. Finally, the OA and PL spectra of photopolymerized ${\mathrm{C}}_{60}$ solid films are presented. The features in both the OA and PL spectra are observed to broaden considerably. In addition, two of the OA bands blueshift slightly (400\char21{}800 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) and the PL features downshift by \ensuremath{\sim}330 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ upon polymerization. These results are consistent with the intermolecular oligomerization bond disorder and reduced symmetry of the ${\mathrm{C}}_{60}$ shell imposed by the covalent bonds between ${\mathrm{C}}_{60}$ molecules in the polymeric phase.