Effects of copper addition to formamidinium/cesium-based perovskite solar cells

Organic-inorganic hybrid perovskite solar cells are expected to be alternative photovoltaic devices of solar cells, because of their high conversion efficiency, easy fabrication process and low cost. On the other hand, the problems are reduced durability due to the volatility of organic cations and toxic lead. One of the effective methods is to introduce additives into the perovskite photoactive layer. By adding copper (Cu) to the perovskite, new orbitals are generated at the upper end of the valence band due to Cu-iodine bonding, resulting in narrower energy gaps. Short-circuit current density is expected to be improved as the concentration of excited carriers increases.