Electronic and Optical Properties of the Spiro-MeOTAD Hole Conductor in Its Neutral and Oxidized Forms: A DFT/TDDFT Investigation

By Simona Fantacci, F. De Angelis, Md. K. Nazeeruddin, M. Graetzel. 2011

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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 light-emitting 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 efficien...

Subfields: Electrical and Electronic Engineering, Polymers and Plastics

View Paper: https://www.semanticscholar.org/paper/e9e938e51c6ef9e87b15cadaa5a40ed0b8be2edb