SiO2/TiO2 based hollow nanostructures as scaffold layers and Al-doping in the electron transfer layer for efficient perovskite solar cells

Abstract

Perovskite solar cells (PSCs) have been developed intensively recently due to their excellent efficiency. In this study, PSCs were fabricated using a hollow structure as a scaffold layer and Al doped TiO₂ (Al-TiO₂) as a compact layer. The hollow structure showed effective loading of perovskite (CH₃NH₃PbI₃Cl_3−x) on the working electrode of the PSCs. In particular, using SiO₂/TiO₂ hollow nanoparticles (STHNPs) instead of TiO₂ hollow nanoparticles (THNPs) as insulators improved the open circuit voltage, because STHNPs did not allow photogenerated electrons to transfer easily from the perovskite. Al-TiO₂ compact layers synthesized using a low temperature procedure (≤150 °C) promoted electron extraction and reduced the recombination, leading to enhanced power conversion efficiency (PCE). An optimum PCE of 14.7% was achieved for PSCs based on STHNP scaffold layers with Al doping in the electron transfer layer.