Mesoporous TiO<sub>2</sub> Electron Transport Materials Derived from 2D Ti-MOFs for Enhanced Power Conversion Efficiency in Printed Mesoscopic Perovskite Solar Cells
Hang Yang, Jianhong Zhao, Tong Zhou, Hengbing Zhang, Weilong Zhang, Jin Zhang, Guangzhi Hu, Yumin Zhang, Qingju Liu
Abstract
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 TiO 2 (M-N-TiO 2 ) derived from two-dimensional titanium metal–organic frameworks (2D Ti-MOFs) is utilized as the electron transport material. The results reveal that M-N-TiO 2 exhibits superior characteristics compared to commercial TiO 2 (P25), including increased porosity, larger specific surface area, and bigger diameter. Due to the enhanced contact between M-N-TiO 2 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-TiO 2 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-TiO 2 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-TiO 2 -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.