Polyaniline/Nickle oxide hole transport layers to increase stability and efficiency of regular perovskite solar cells

While hybrid perovskite solar cells (HPSCs) currently reach an efficiency as high as 25.8% and are comparable with commercial silicon solar cells, they still suffer from low stability against external environmental conditions. The best way to protect the perovskite active layer from degradation caused by humidity is the development of dopant-free or inorganic hole transport layers (HTLs). In the current study, we developed a novel and low-cost HTL based on the doping of polyaniline (PANI) with nickel oxide (NiOx) nanoparticles with hydrophobic property. For this aim, PANI solutions in chloroform were mixed with different amounts of NiOx material in a range of 0%-10% in volume ratio and spin-coated over the pre-formed perovskite layer. It was found that introducing 7.5% of NiOx material into the PANI stock solution improved the HTL role of the PANI layer and led to a champion efficiency of 14.27% for related PSC devices, 13.2% higher than the pure PANI-based PSCs, and 54.9% higher than HTL-free PSCs. Results showed that NiOx material facilitates hole extraction to the top electrode and reduces the electron-hole recombination rate in PSC devices. Besides, the higher stability of PSCs that was achieved with developed HTL compared with HTL-free devices.