Enhancing the Performance of the Mesoporous TiO2 Film in Printed Perovskite Photovoltaics through High‐Speed Imaging and Ink Rheology Techniques

Mesoscopic carbon‐based perovskite solar cells (C‐PSCs) have the potential to be manufactured at an industrial scale by utilizing screen‐printing, a simple, affordable, and commercially mature process. As such, many recent publications have focused on enhancing performance through modifying cell architecture and perovskite chemistries. This work examines how ink rheology can be tuned to optimize cell performance through reducing the occurrence of common print defects to create higher quality m‐TiO2 films. Inks with different solvent dilutions and rheological profiles are assessed using high‐speed imaging through the screen‐printing visualization (SPV) technique, to investigate the impact of the viscosity and elasticity on ink separation mechanisms. The resultant film quality and its influence on device performances are then assessed. Ink separation lengths are minimized, and the formation of filaments ceases during printing, leading to improved TiO2 film topography and homogenous infiltration of the perovskite precursor. Consequently, PCE is improved by over 10% of the original efficiency in cells and 224 cm2 active area modules due to enhanced Voc and FF. These results not only provide key insights into tailoring ink rheology, to achieve improved print homogeneity and higher performing cells, but also aid further work on enhancing the performance of other screen‐printed functional films. Mesoscopic carbon‐based perovskite solar cells (C‐PSCs) offer good stability, low‐cost fabrication, and commercial scalability via screen‐printing. This work examines how ink rheology can be tuned to optimize cell performance by improving m‐TiO2 film quality. Ink separation lengths are minimized, and filament formation ceases during printing, enabling improved TiO2 film topography and homogenous infiltration of the perovskite precursor, increasing cell power conversion efficiency (PCE).