Tuning halide perovskite energy levels

in Energy and Environmental Science (2020)

Solar energy is playing a significant role in the development of a world powered by clean energy sources. In this context, halide perovskite solar cells (PSCs) are considered one of the most promising ... [more ▼]

Solar energy is playing a significant role in the development of a world powered by clean energy sources. In this context, halide perovskite solar cells (PSCs) are considered one of the most promising research lines thanks to their high efficiencies and flexibility, combined with an easy and cheap fabrication process. The possibility of combining different materials and compositions is an excellent advantage of PSCs. However, still, a big limit is posed by the need for a proper energy level alignment between the layers of materials comprising devices. Therefore, it is of utmost interest to develop methods allowing to tune the energy levels of the different materials. In semiconductors physics, a common technique to achieve this purpose is to functionalize the surface of the materials with dipolar molecules. Nevertheless, this has been rarely applied to perovskites because of the highly rough surface of the films. In this study, we show that it is possible to use this technique in hybrid organic–inorganic perovskite semiconductors systematically and tune the direction and magnitude of the shift by controlling the deposition process. These findings offer a toolbox to simplify the application of halide perovskites in optoelectronic devices. [less ▲]