Bulk intermixing-type perovskite CH₃NH₃PbI₃/TiO₂ nanorod hybrid solar cells

To replace high-temperature sintered scaffold materials in conventional CH3NH3PbI3-based solar cells, this study demonstrates a new device structure of a bulk intermixing (BI)-type CH3NH3PbI3/TiO2 nanorod (NR) hybrid solar cell, where dispersed TiO2 NRs from chemical synthesis are intermixed with the perovskite absorbing layer to form a BI-type perovskite/TiO2 NR hybrid for device fabrication. Through interface engineering between the TiO2 NR surface and the photoactive perovskite material of CH3NH3PbI3 by ligand exchange treatment, a remarkable power conversion efficiency (PCE) of over 12% was achieved based on the simple BI-type CH3NH3PbI3/TiO2 NR hybrid device structure. The proposed hybrids not only provide great flexibility for deposition on various substrates through spin coating at low temperatures but also enable layer-by-layer deposition for the future development of perovskite-based multi-junction solar cells.