Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Publication date: 6th February 2020
Hybrid organometal halide perovskite solar cells (PSCs) are a potentially low-cost and efficient photovoltaic technology, however, fundamental questions on the mechanisms of charge separation, charge extraction at the selective contacts, and recombination processes still remain. In addition, the perovskite material presents a chemical instability that needs to be addressed. There are several reports on the effect of preparation method, perovskite composition and cell configuration on the performance and stability of the solar cell performance, but there is no unifying explanation as of yet. PSCs emerged from the dye-sensitized solar cell (DSSC) and organic photovoltaics (OPV), and the device architecture can be divided into two different groups: mesoscopic and planar cells. Advantages and disadvantages of using either of these architectures for future scale-up and commercialization are still under debate since both have demonstrated certified efficiencies in excess of 20%.
The aim of this work is two-fold: (i) to investigate the effect of different electron selective contacts (ESC) on the general performance and small-perturbation response of mesoscopic perovskite solar cells; and (ii) to test the stability of non-encapsulated planar and mesoscopic devices containing TiO2 as ESC prepared at low temperatures in air under conditions of relatively high humidity (60% RH ± 5%). For this purpose, various crystalline structures of titanium dioxide, zinc stannate as well as the insulators zirconia and alumina were studied as ESC or scaffolds in the mesoscopic configuration. Our main findings include a clear correlation between the efficiency of charge separation at the ESC/MAPI interface (as evidenced by photoluminescence measurements) and the photovoltaic and hysteresis behavior of the solar cell device [1]. In the second study, the results indicate that the presence of a mesoporous ESC may improve the lifetime of the cells, related to the speed of electron extraction from the perovskite layer, thus preventing a light induced degradation mechanism [2].