by Samuele Lilliu | 19 December 2022
In-situ Simultaneous Photovoltaic and Structural Evolution of Perovskite Solar Cells
This video is part of the supporting information for an article I published in Energy and Environmental Science In situ simultaneous photovoltaic and structural evolution of perovskite solar cells during film formation
Abstract. Metal-halide perovskites show remarkably clean semiconductor behaviour, as evidenced by their excellent solar cell performance, in spite of the presence of many structural and chemical defects. Here, we show how this clean semiconductor performance sets in during the earliest phase of conversion from the metal salts and organic-based precursors and solvent, using simultaneous in situ synchrotron X-ray and in operando current–voltage measurements on films prepared on interdigitated back-contact substrates. These structures function as working solar cells as soon as sufficient semiconductor material is present across the electrodes. We find that at the first stages of conversion from the precursor phase, at the percolation threshold for bulk conductance, high photovoltages are observed, even though the bulk of the material is still present as precursors. This indicates that at the earliest stages of perovskite structure formation, the semiconductor gap is already well-defined and free of sub-gap trap states. The short circuit current, in contrast, continues to grow until the perovskite phase is fully formed, when there are bulk pathways for charge diffusion and collection. This work reveals important relationships between the precursors conversion and device performance and highlights the remarkable defect tolerance of perovskite materials.
The graphs shown in this video are the result from a large data set of X-Ray diffraction image analysis from GI-WAXS measurements performed at the ESRF. My MATLAB application outputs a series of images which are then imported into After Effects and used to generate this video.