Temperature Dependent Photocurrent Mapping in Halide Perovskite Photovoltaics

The current global photovoltaic market is almost exclusively composed of silicon-based solar cells. Nonetheless, the power conversion efficiency (PCE) of these cells has only increased by 1.6% over the past 17 years. Hybrid organic-inorganic metal halide perovskite compounds, such as methylammonium lead iodide (MAPbI₃), however, have leapt from PCEs of 3% to over 20% in just the last five years. Due to this rapid progress, emerging solar cells based on these materials have already begun to rival silicon photovoltaic efficiencies. In fact, many experts anticipate that perovskite solar cells will be one of the cheapest and most versatile photovoltaic technologies of the future. Fundamental understanding of the underlying perovskite material physics is critical to developing improved perovskites with reduced toxicity, increased stability, and removal of hysteresis in their electronic devices. We have performed temperature and external electric field dependent scanning photocurrent microscopy on single- and poly-crystalline MAPbI₃ samples in order to discern the dominating charge transport mechanism, among ferroelectricity, ion migration, charge traps, and field-screening, which governs the unique characteristics of the halide perovskite materials.