Synergistic effects of three-dimensional orchid-like TiO2 nanowire networks and plasmonic nanoparticles for highly efficient mesoscopic perovskite solar cells

Abstract

TiO₂ nanoparticle (TiO₂ NP)-based mesoscopic electron transport structures have been frequently used in organic–inorganic hybrid perovskite solar cells (PSCs) for rapid electron transport. However, TiO₂ NPs that are densely agglomerated in the scaffold layer may inhibit the penetration of a perovskite solution thereby deteriorating the device performance. Here, we use three-dimensional orchid-like TiO₂ nanowires (OC-TiO₂ NWs) as scaffold materials to overcome the deficiencies of TiO₂ NP-based structures. The perovskite precursor deeply infiltrated into the spacious pores within the OC-TiO₂ NW network and crystallized in the scaffold layer, which increased the recombination resistance and charge extraction efficiency. Additionally, Ag NPs were introduced in the form of a silica-coated Ag@OC-TiO₂ NW (SiO₂@Ag@OC-TiO₂ NW) composite to achieve still better performance through localized surface plasmon resonance (LSPR) and exciton dissociation inducement of the Ag NPs. Consequently, a PSC based on this collaborative scaffold consisting of Ag NPs and OC-TiO₂ NWs exhibited a high power conversion efficiency (PCE) of 15.09%, which is an improvement of 24% over a PSC based on a TiO₂ NP scaffold layer, where the average PCE was 12.17%.