RESUMEN
The dark red semiconductor Cu(Sb2S3)Cl was obtained by leaching the layered precursor Cu(Sb2S3)[AlCl4] in a 0.1 M aqueous HCl solution. The selective extraction of AlCl3 yielded a mica-like lamellar product of poor crystallinity. Misalignment of lamellae down to the nanoscale prevented structure determination by conventional single-crystal X-ray diffraction, but a combination of transmission electron microscopy, selected area electron diffraction, and selected area electron precession diffraction tomography on a nanoscale spot with largely ordered crystalline lamellae revealed the crystal structures of two intergrown modifications. Orthorhombic o-Cu(Sb2S3)Cl and monoclinic m-Cu(Sb2S3)Cl have similar layers to the precursor and differ only in the stacking of the layers. These consist of uncharged Sb2S3 strands, whose sulfide ions, together with chloride ions, coordinate the copper(I) cations. Only one chloride ion remained from the [AlCl4]- group. DFT calculations confirm the structure solution for the orthorhombic form and suggest that the monoclinic structure is metastable against transformation to o-Cu(Sb2S3)Cl.
RESUMEN
One-dimensional (1D) perovskites (perovskitoids) occupy an important place among modern semiconducting materials, offering design flexibility together with a wide range of properties. However, most such materials have a large bandgap, which limits their application in photovoltaics. Here, we present a new 1D hybrid perovskite containing the functional cation aminophenyl viologen (APhV). Similar to other materials from the viologen perovskite family, aminophenyl viologen iodidoplumbate(II) (APhV[Pb2I6]·2NMP) exhibits a broad absorption with a narrow and direct bandgap of 1.66 eV, which was calculated from the experimental data and is supported also by our first-principles simulations. Close contact between electron-rich inorganic chains and electron-accepting viologen molecules suggests charge transfer within the hybrid, which is also visible in the density of states. Considering its reasonable thermal stability, aminophenyl viologen iodidoplumbate can find a wide application in photovoltaics.