Defect States in Hybrid Perovskites for Photovoltaic and Sensing Applications

Hybrid perovskites based on methylammonium lead iodide/bromide (CH₃NH₃PbI₃/Br₃) have recently emerged as highly promising materials for photovoltaic applications and X-ray detection. Despite encouraging results, these materials still suffer from significant stability issues, particularly when used as active layers in thin-film solar cells. One of the main causes of this instability is believed to be the presence of lattice defects.

The aim of this experimental study is to gain a deeper understanding of the role of defects in charge transport and collection mechanisms in these materials. Specifically, we investigate single crystals, polycrystals, and two-dimensional films to explore the impact of surfaces, interfaces, and grain boundaries.

Defect states are analyzed as a function of perovskite composition using advanced electrical characterization techniques, including current–photo-voltage and capacitance–voltage measurements as a function of temperature. Charge collection spectroscopic methods are also employed, such as PICTS (Photoinduced Transient Spectroscopy), DLTS (Deep Level Transient Spectroscopy), and surface photo-voltage and photo-current spectroscopy.

The project is funded by POR-FESR Emilia-Romagna and the PRIN-PNRR 2022.