Interfacial engineering by p-methylphenylmethylammonium iodide for efficient carbon counter electrode (CE)-based 2D/3D hybrid perovskite solar cells

Defects at the surface and grain boundaries of three-dimensional (3D) organic-inorganic metal halide perovskite films lead to the non-radiative recombination of charge carriers and accelerate perovskite decomposition. In turn, this deteriorates the power conversion efficiency ( PCE ) and stability of perovskite solar cells (PSCs). Herein, p -methylphenylmethylammonium iodide ( p -MePMAI) was reacted with a 3D perovskite to in - situ form a two-dimensional (2D) perovskite upper layer. This upper layer passivated the surface and grain boundary defects of the 3D perovskite film, improving its surface hydrophobicity . As a result, a carbon counter electrode (CE)-based 2D/3D PSC achieved a maximum PCE of up to 15.63%, which was much higher than that of an unmodified 3D MAPbI 3 PSC (12.16%). Moreover, the unencapsulated 2D/3D device maintained 80% of its initial PCE after exposure to air for 700 h with a relative humidity (RH) of 40 ± 5%. This research opens a new pathway for the successful construction of stable and efficient 2D/3D PSCs with organic ammonium salts .