Mesoscopic Perovskite Solar Cells: Efficiency Enhancement via Optimization of the Titania Anode

Abstract

The most common perovskite-based solar cell architecture is the mesoscopic perovskite solar cell. Its structure employs a compact layer and a mesoporous metal oxide layer as the cell anode. Typically, the anode consists of titania, which is an n-type semiconductor. The compact layer acts as a blocking layer by preventing the recombination of charges. The mesoporous layer extracts electrons from the excited perovskite upon light absorption, and transports them to the electrode. The present Thesis studies the effect of titania anode modification on the power conversion efficiency of mesoscopic perovskite solar cells. The experiments carried out include the fabrication and the characterization of titania-based mesoscopic solar cells. The research methods used in this work are scanning electron microscopy, steady-state absorption and reflectance spectroscopies, and I-V measurements. The titania anode, i.e. the compact and mesoporous layer, was optimized as the result of the study. The best solution to produce compact titania layer by spin-coating was found. It was observed that the mesoscopic perovskites solar cells with highest efficiency had a thin mesoporous titania layer. Among the tested thicknesses, 190 nm was the optimal value for the mesoporous layer thickness, leading to the best cell performance. The highest achieved efficiency of the solar cells prepared in this work was 9.55 %.