A conducting polymer of lignosulfonic
acid-grafted, polyaniline-doped camphorsulfonic acid (LS-PANI-CSA),
created via a low-temperature solution process, has been explored
as an efficient hole-transport layer (HTL) for inverted single cation–anion
CH3NH3PbI3 perovskite solar cells.
The performance of the solar cell was optimized in this study by tuning
the morphology and work function of LS-PANI-CSA films using dimethylsulfoxide
(DMSO) as a solvent in treatment. Results showed that DMSO washing
enhanced the electronic properties of the LS-PANI-CSA film and increased
its hydrophobicity, which is very important for perovskite growth.
The perovskite active layer deposited onto the DMSO-treated LS-PANI-CSA
layer had higher crystallinity with large grain sizes (>5 μm),
more uniform and complete surface coverage, and very low pinhole density
and PbI2 residues compared to untreated LS-PANI-CSA. These
enhancements result in higher device performance and stability. Using
DMSO-treated LS-PANI-CSA as an HTL at 15 nm of thickness, a maximum
10.8% power conversion efficiency was obtained in ITO/LS-PANI-CSA/MAPbI3/PCBM/BCP/Ag inverted-device configurations. This was a significant
improvement compared to 5.18% for devices based on untreated LS-PANI-CSA
and a slight improvement over PEDOT:PSS-based devices with 9.48%.
Furthermore, the perovskite based on treated LS-PANI-CSA showed the
higher stability compared to both untreated LS-PANI-CSA and PEDOT:PSS
HTL-based devices.