Hybrid Organic–Inorganic Coordination Complexes as Tunable Optical Response Materials

Novel lead and bismuth dipyrido complexes
have been synthesized and characterized by single-crystal X-ray diffraction,
which shows their structures to be directed by highly oriented π-stacking
of planar fully conjugated organic ligands. Optical band gaps are
influenced by the identity of both the organic and inorganic component.
Density functional theory calculations show optical excitation leads
to exciton separation between inorganic and organic components. Using
UV–vis, photoluminescence, and X-ray photoemission spectroscopies,
we have determined the materials’ frontier energy levels and
show their suitability for photovoltaic device fabrication by use
of electron- and hole-transport materials such as TiO2 and
spiro-OMeTAD respectively. Such organic/inorganic hybrid materials
promise greater electronic tunability than the inflexible methylammonium
lead iodide structure through variation of both the metal and organic
components.