Mesoporous TiO₂ Electron Transport Materials Derived from 2D Ti-MOFs for Enhanced Power Conversion Efficiency in Printed Mesoscopic Perovskite Solar Cells

Printed mesoscopic perovskite solar cells (PM-PSCs) are promising for industrial production and large-scale applications due to their advantageous traits of low cost, simple fabrication, and outstanding stability. Nevertheless, in the absence of a hole transport layer to extract holes and poor interfacial contact during the procedure of printing, PM-PSC structures typically suffer from low efficiency and carrier recombination. Herein, a mesoporous nanocrystal TiO2 (M-N-TiO2) derived from two-dimensional titanium metal–organic frameworks (2D Ti-MOFs) is utilized as the electron transport material. The results reveal that M-N-TiO2 exhibits superior characteristics compared to commercial TiO2 (P25), including increased porosity, larger specific surface area, and bigger diameter. Due to the enhanced contact between M-N-TiO2 and perovskite as well as the increased filling of perovskite within the mesoporous layer, a consequential improvement in perovskite crystallization is observed. This accelerates the electron extraction process and decreases the rate of carrier recombination. Simultaneously, the presence of organic molecules in M-N-TiO2 contributes to the effective passivation of perovskite defects, consequently reducing recombination losses. Owing to the synergistic effect of electron extraction promotion and recombination losses, the fabricated PM-PSC based on M-N-TiO2 delivers a champion power conversion efficiency (PCE) of 15.66% with an improved FF of 74.09% compared with the P25-based device. Furthermore, long-term stability is achieved with the M-N-TiO2-based device. This investigation provides a novel approach to the selection of electron transport materials to enhance both the efficiency and stability of PM-PSCs