The molecular structures and electronic and optical properties of 2,2'7,7'-tetrakis-(N,N-di-p-methoxyphenyl amine)-9,9'-spirobifluorene (spiro-MeOTAD) in different oxidation states have been investigated by means of DFT/TDDFT methods. Spiro-MeOTAD has been demonstrated to be an efficient hole-transport material (HTM) in organic lightemitting devices (OLEDs) and in solid-state dye-sensitized solar cells (ssDSCs), and to date spiro-MeOTAD, has yielded the highest ssDSC efficiency. The spiro-MeOTAD radical cation exhibits long-term stability, even though the 2+ and 4+ formal oxidation states are accessible. DFT and TDDFT allow the characterization of the excited states involved in the absorption processes of the spiro-MeOTAD-derived cations, an important aspect considering that the oxidized species absorb in the visible region. The excellent agreement between theory and experiment for both neutral' spiro-MeOTAD and its oxidized forms opens the possibility for identifying the features that make it an efficient HTM, thus helping in the design of chemically modified or substituted spirobifluorenes.
Electronic and Optical Properties of the Spiro-MeOTAD Hole Conductor in Its Neutral and Oxidized Forms: A DFT/TDDFT Investigation
De Angelis, Filippo;
2011
Abstract
The molecular structures and electronic and optical properties of 2,2'7,7'-tetrakis-(N,N-di-p-methoxyphenyl amine)-9,9'-spirobifluorene (spiro-MeOTAD) in different oxidation states have been investigated by means of DFT/TDDFT methods. Spiro-MeOTAD has been demonstrated to be an efficient hole-transport material (HTM) in organic lightemitting devices (OLEDs) and in solid-state dye-sensitized solar cells (ssDSCs), and to date spiro-MeOTAD, has yielded the highest ssDSC efficiency. The spiro-MeOTAD radical cation exhibits long-term stability, even though the 2+ and 4+ formal oxidation states are accessible. DFT and TDDFT allow the characterization of the excited states involved in the absorption processes of the spiro-MeOTAD-derived cations, an important aspect considering that the oxidized species absorb in the visible region. The excellent agreement between theory and experiment for both neutral' spiro-MeOTAD and its oxidized forms opens the possibility for identifying the features that make it an efficient HTM, thus helping in the design of chemically modified or substituted spirobifluorenes.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
