Insights into HTM-Free Mesoporous Perovskite Solar Cells with a Carbon Electrode Using Electrochemical Impedance Spectroscopy Analysis

Hole-transport material (HTM)-free mesoporous perovskite solar cells (PSCs) with a carbon electrode are of great interest because they can be fabricated using inexpensive carbon materials and simple screen-printing methods. In this work, we investigated the influence of the components on photovoltaic performance of HTM-free mesoporous PSCs with a carbon electrode using electrochemical impedance spectroscopy analysis. The results showed that the series resistance was increased as the thickness of the compact layer and mesoporous ZrO₂ layers increased, whereas it decreased with increasing thickness of mesoporous TiO₂ and carbon layers. It was also found that charge transfer resistance decreases with increasing thickness of mesoporous TiO₂, ZrO₂ and carbon layers, and charge recombination resistance is mainly influenced by the compact layer, mesoporous TiO₂ and ZrO₂ layers, and the chemical capacitance during charge recombination is mainly influenced by the mesoporous TiO₂ layer. The efficiency of the device fabricated using the optimized parameters was 15.05%.