Impact of pre and post-perovskite infiltration treatments on monolithic perovskite solar cell performance

Abstract

Carbon-based monolithic perovskite solar cells (mPSCs) represent an enticing frontier in the domain of organic–inorganic hybrid solar cells, capturing substantial research attention due to their cost effectiveness and straightforward fabrication process. Despite these merits, the challenge of achieving uniform pore filling in mPSCs, especially within mesoporous layers comprising titania, zirconia, and carbon alongside perovskite, persists. The uncontrolled and confined crystallization of the perovskite precursor within these mesoporous layers warrants meticulous investigation. This study addresses the issues related to uncontrolled crystallization by employing temperature-assisted infiltration techniques spanning from room temperature to 70 °C across triple mesoporous scaffolds. Devices were intricately fabricated using a semi-automatic drop-casting procedure, incorporating a (5-AVA)x(MA)1−xPbI3-mixed cation perovskite. Following infiltration, comprehensive pore filling of oxide layers was achieved through chlorobenzene-assisted antisolvent treatment. Comparisons were made between chlorobenzene-assisted and untreated samples under ambient conditions and thermal stress (40–70 °C). The temperature-dependent effects on perovskite infiltration and recrystallization were systematically investigated through dark and light current–voltage (J–V) characteristics, Impedance Spectroscopy (IS), and X-ray Diffraction (XRD) analyses. The findings revealed that the optimum power conversion efficiency (PCE) of 13.34% was attained when perovskite infiltration occurred at 40 °C with antisolvent treatment. Dark J–V and IS results indicated that temperature-assisted infiltration not only stimulated charge transfer but also effectively suppressed recombination. Under chlorobenzene treatment, XRD peaks exhibited broadening, indicating a reduction in perovskite crystallite size. This phenomenon facilitated the development of perovskite crystals across all available mesoporous spaces, leading to an enhanced interface property conducive to efficient charge transfer. The insights gleaned from this study on the controlled crystallization of perovskite precursors within mesoporous layers hold significant promise for advancing the stability and efficiency of mPSCs.