PUB - Publikationen an der Universität Bielefeld

Nickel oxide (NiO_1+δ) is a versatile material used in various fields such as optoelectronics, spintronics, electrochemistry, and catalysis which is prepared with a wide range of deposition methods. Herein, for the deposition of NiO_1+δfilms, the reactive gas flow sputtering (GFS) process using a metallic Ni hollow cathode is developed. This technique is distinct and has numerous advantages compared to conventional sputtering methods. The NiO_1+δfilms are sputtered at low temperatures (100 ºC) for various oxygen partial pressures during the GFS process. Additionally, Cu‐incorporated NiO_1+δ(Cu_xNi_1−xO_1+δ) films are obtained with 5 and 8 at% Cu. The thin films of NiO_1+δare characterized and evaluated as a hole‐transporting layer (HTL) in perovskite solar cells (PSCs). The NiO_1+δdevices are benchmarked against state‐of‐the‐art self‐assembled monolayers (SAM) ([2‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (also known as MeO2PACz)‐based PSCs. The best‐performing NiO_1+δPSC achieves an efficiency (η) of ≈16% without a passivation layer at the HTL interface and demonstrates better operational stability compared to the SAM device. The findings suggest that further optimization of GFS NiO_1+δdevices can lead to higher‐performing and more stable PSCs.