Organic-inorganic hybrid composites for photovoltaics: Organic guest molecules embedded in μc-Si and ZnSe host matrices

摘要

The concept of organic-inorganic hybrid composites for bulk sensitization of inorganic semiconductors by organic dye molecules is introduced. The idea is either to increase the absorptivity of e.g. indirect semiconductors as μc-Si or to expand in a two-step process the absorption spectrum of wide gap semiconductors to photons of energy smaller than the band gap. The composites are prepared by vacuum-based codeposition. Raman and optical spectroscopy, and photoemission have been used to prove the stability of the organic molecules ZnPc and F_(16)ZnPc for the applied growth conditions. Enhancement of photoconductivity has been shown for ZnPc-Si bilayer. As a crucial parameter for the transfer of excited charges, the alignment of dye HOMO-LUMO states versus semiconductor band edges has been determined using photoelectron spectroscopy.