Thermally and Air Stable Perovskite Solar Cells with a Hole Transporting PTAA/NiO Bilayer

Organic/inorganic halide perovskite materials have attracted substantial attention in solar cells, and they have achieved significant improvements in recent years. In perovskite solar cells (PSCs), the engineering of interfacial properties between multilayers is an important determinant of performance and stability. Here, we designed a bilayer structure of hole transporting layer by inserting poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), which can improve the interfacial properties between the perovskite and the nickel oxide (NiO) hole transport layer in p-i-n planar PSCs. We observed that the hole transporting PTAA/NiO bilayer leads to higher performance by optimizing the energy level and accelerating the extraction of charges from the interface. The power conversion efficiency of the PSC was improved from 17.29% to 19.05% when the PTAA/NiO bilayer was introduced instead of the NiO monolayer. Ultimately, we confirmed that this interface engineering provides thermal and air stability of PSCs.