In-situ growth of perovskite-type LaBO3 (B = Ni, Co, Fe, Mn) films by metal oleate route

It is still challenged to propose a straightforward and in-situ growth method of fabricating perovskite-type metal oxide films with dense and uniform surface coverage. This paper presents a simple strategy to prepare LaBO 3 (where B = Ni, Co, Fe, Mn) films by metal oleate (MO) route, in which metal oleates (La(OA) 3 and (B(OA) x , x  = 2 or 3) serve as effective ligands to inhibit the self-aggregation among crystal grains. The as-prepared LaNiO 3 film with uniform and dense surface shows a reduced contact angle (31.5° vs 51.2°) and surface roughness (Ra = 14.2 vs 23.9 nm) compared with film prepared by Sol-gel (SG) method. Finally, the LaNiO 3 film by MO route is successfully employed as hole transport layer (HTL) in perovskite solar cells (PSCs) to obtain a power conversion efficiency (PCE) up to 15.62 %, which is 1.54 times that of PSCs by SG method. This work opens an avenue for fabricating LaBO 3 films with dense and uniform surface coverage by MO route.