TCO-free perovskite solar cells in taking advantage of SWCNT/TiO2 core/shell sponge

A nanohybrid of titanium dioxide (TiO2) and single-walled carbon nanotubes (SWCNTs) with dual functions of collecting electrons and transparent electrode layer is synthesized by nano-cluster deposition technology. The super-hollow structure of the SWCNTs was directly fabricated via arc discharge and fully covered with a thin layer (∼15 nm) of TiO2, which formed the SWCNT/TiO2 core/shell sponge. The developed SWCNT/TiO2 core/shell sponge is used directly as scaffolding for a light absorber and electron collector in transparent conducting oxide (TCO) electrode-free perovskite solar cells (PSCs) for the first time, which exhibited a power conversion efficiency of 7.2%. The large surface area of the core/shell bundle is sufficiently effective in transferring the photogenerated electron from the Perovskite absorber to the SWCNTs. More importantly, the findings of this work could support the concept of replacing the conventional TCO in PSCs and pave the way to further work for developing inexpensive and flexible PSCs.