Steady-state optoelectronic measurements of halide perovskites on a selective contact: a path to in-depth comprehension of their photovoltaic activity

Most of the charge transport properties in halide perovskite (HaP) absorbers are measured by transient measurements with pulsed excitations; however, most solar cells in real life function in steady-state conditions. In contrast to working devices that include selective contacts, steady-state measurements need as high as possible photoconductivity (sigma ph), which is typically restricted to the absorber alone. In this paper, we enabled steady-state charge transport measurement using atomic layer deposition (ALD) to grow a conformal, ultra-thin (similar to 4 nm) ZnO electron transport layer that is laterally insulating due to its thickness. Due to the highly alkaline behavior of the ZnO surfaces, it readily reacts with halide Perovskites. ALD process was used to form an Aluminum oxynitride (AlON) thin (similar to 2 nm) layer that passivates the ZnO-HaP interface. We show that the presence of the AlON layer prevents HaP degradation caused by the interaction with the ZnO layer, improves the HaP sigma ph, and doubles the HaP carrier diffusion lengths.