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/cm(2)) and the fill factor also improved, eventually leading to a power conversion efficiency enhancement from 6.59 to 10.90%. (C) 2016 Elsevier Ltd. All rights reserved.