Polygermyne: Germanium sheet polymers with efficient near-infrared luminescence

摘要

The structural, optical and electronic properties of the Ge sheet polymer poylgermyne are summarized. Prepared via topotactic transformation of Zintl-phase CaGe_2, (GeH)_n forms a layered crystal in a tr6 stacking sequence with a distance of 5.65 A between adjacent layers. The photoluminescence at 1.3 eV is excited nearly resonantly with a Stokes shift of 0.2 eV. Together with band structure calculations this shows that polygermyne has a direct band gap.