Improving the Performance of Perovskite Solar Cells using a Polyphosphazene Interfacing Layer

Herein, the impact of thin layer of polyphosphazene derivatives, as a buffer layer between the electron-transporting layer and the back metal-contact in mixed-cation mixed-halide perovskite solar cells (PSCs), is explored. PSCs with a poly[bis(allylamino)phosphazene] (PPz) interlayer exhibit enhanced rectification in the photo-induced current density-voltage (J-V) curves, which show improved photovoltaic performance and photostability with reduced hysteresis. The thickness of the interlayer is optimized and the optimized PSCs with PPz buffer layer shows an average open-circuit voltage (V-OC) of approximate to 1.05 V, a short-circuit current density (J(SC)) of around 23.5 mA cm(-2), a fill factor of approximate to 72%, and a power conversion efficiency of about 17.3% for the forward and reverse scans under simulated AM1.5G illumination. Moreover, the application of PPz as an electron-transporting interlayer in organic solar cells reveals that PPz interfacial layer improves the electron extraction at the cathode. The merit of applying PPz interlayer extends to the possibility of using different metals (such as aluminum, gold, copper, and silver) as the top contact in the prepared PCSs. In general, these experiments reveal a very promising approach to tackle the issue of interfacing, and to improve the performance and stability of PSCs.