Morphology control of the perovskite thin films via the surface modification of nickel oxide nanoparticles layer using a bidentate chelating ligand 2,2’-Bipyridine

Controlling the interfacial properties between the substrate and the perovskite layer is a facile way to improve the perovskite film quality. Many self-assembled monolayers (SAMs) with various functional groups have been used to modify the interlayer contact between the substrate and the perovskite layer, via chemical interactions with the two layers. To meet the requirements for high-speed roll-to-roll fabrication of PSCs, it is important to develop anode interlayers that is easy to process to optimize the perovskite morphology. Here we use bidentate chelating ligand 2,2’-bipyridine to modulate the interfacial properties between NiOx and the perovskite, via its strong interactions with the two layers. The improved interfacial contact is beneficial to the crystal growth of the perovskite. The resulting film exhibits more homogeneous morphology with enhanced crystallinity and reduced trap states, in contrast with the perovskite film on the pristine NiOx layer. As a result, the as-prepared inverted PSCs produce improved device performance compared with the reference devices prepared on the pristine NiOx substrates.