Optimizing Lignosulfonic Acid-Grafted Polyaniline as a Hole-Transport Layer for Inverted CH3NH3PbI3 Perovskite Solar Cells

Gailan A Al-Dainy; Fumiya Watanabe; Ganesh K Kannarpady; Anindya Ghosh; Brian Berry; Alexandru S Biris; Shawn E Bourdo

doi:10.1021/acsomega.9b03451

Optimizing Lignosulfonic Acid-Grafted Polyaniline as a Hole-Transport Layer for Inverted CH₃NH₃PbI₃ Perovskite Solar Cells

ACS Omega. 2020 Jan 21;5(4):1887-1901. doi: 10.1021/acsomega.9b03451. eCollection 2020 Feb 4.

Authors

Gailan A Al-Dainy¹, Fumiya Watanabe¹, Ganesh K Kannarpady¹, Anindya Ghosh², Brian Berry², Alexandru S Biris¹, Shawn E Bourdo¹

Affiliations

¹ Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 S. University Ave., Little Rock, Arkansas 72204, United States.
² Department of Chemistry, University of Arkansas at Little Rock, 2801 S. University Ave., Little Rock, Arkansas 72204, United States.

Abstract

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.