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