Dye Sensitized TiO2 and ZnO Charge Transport Layers for Efficient Planar Perovskite Solar Cells: Experimental and DFT Insights

Abstract

In this work, the efficiency improvement of planar perovskite solar cells by the introduction of modified electron transport layers (ETLs) is investigated. To this aim, a cobalt complex dye as sensitizer for TiO2, based on Schiff base ligand (Co-NG), and a ZnO layer were prepared by the sol gel method and are tested. The electrodes and the complex are characterized by x-ray diffraction, TGA/DSC and UV–Vis spectroscopy. The photo-physical properties of Co-NG complex investigated at the molecular level show that the dye exhibits good optical behavior with two maxima around 415 nm and 604 nm and a high molar extinction coefficient equal to 27.5 × 103 M−1 cm−1. The influence of sensitization on the optical properties of the ETLs is tested and strong interactions between the dye and the ETLs are found. As a result, the solar cell performances of TiO2/Co-NG and ZnO/Co-NG exhibit a significant efficiency increase equal to 18.94% and 16.32%, respectively, compared to the reference solar cells