Fabrication of visible‐light transparent solar cells composed of NiO/Ni x Zn 1‐x O/ZnO heterostructures

Visible‐light transparent solar cells were fabricated using p ‐type NiO and n ‐type ZnO by conventional RF reactive sputtering with NiZnO alloy as an intrinsic interlayer. The energy band diagrams of NiO/NiZnO/ZnO heterojunctions were revealed by photoelectron yield spectroscopy, and the band gap energies were estimated to be 1.2 eV for NiO/Ni 0.4 Zn 0.6 O and 0.6 eV for Ni 0.4 Zn 0.6 O/ZnO heterojunctions. By using In 2 O 3 :Sn (ITO) as a transparent electrode in NiO‐based visible‐light transparent solar cells, a small but noticeable photovoltaic effect was obtained. The short‐circuit current density (J sc ) increased from 4 μA/cm 2 to 12 μA/cm 2 due to the insertion of Ni 0.4 Zn 0.6 O interlayer. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)