Low-cost and efficient perovskite solar cells using a surfactant-modified polyaniline:poly(styrenesulfonate) hole transport material

Highlights: • PANI:PSS modified with a nonionic surfactant (Triton X–100) was successfully utilized as a hole transport material for perovskite solar cells. • Perovskite solar cells using PANI:PSS with the optimal Triton X–100 concentration exhibited a maximum power conversion efficiency of 11.67%. • Triton X–100 played a bifunctional role to enhance the hole extraction capability of PANI:PSS. - Abstract: A facile synthesis and modification method of polyaniline:poly(styrenesulfonate) (PANI:PSS) is reported for an efficient hole transport material (HTM) in inverted planar perovskite solar cells (PSCs). PANI:PSS with Triton X–100, a nonionic surfactant, showed enhanced hole transport capability due to improved wetting on the substrate and a surface compositional change. The surfactant lowered the surface tension of a PANI:PSS aqueous solution, which enabled uniform casting of PANI:PSS films onto an indium tin oxide (ITO) substrate without any surface treatment. Additionally, self-organization of PSS nanogranules, induced by the surfactant, provided PANI-rich surfaces that were favorable for hole extraction. When surfactant-modified PANI:PSS (1.0 wt% Triton X–100) was used as an HTM in a PSC, the average short-circuit current density increased by 23% compared with pristine PANI:PSS (i.e., from 15.02 to 18.43 mA/cm²) and the fill factor also improved, eventually leading to a power conversion efficiency enhancement from 6.59 to 10.90%.