Passivation in perovskite solar cells: A review

Photovoltaic device based on inorganic–organic hybrid perovskite structured materials have been one of the brightest spotlights in the energy-conversion research field in recent years. However, due to their inherent properties and the architecture of the fabricated device, many defects trap states or carrier transport barriers are present at the interfaces between each functional layer and at the grain boundaries of the perovskite. These defects cause undesirable phenomena such as hysteresis and instability in the perovskite solar cells, which has slowed their commercialization. To address these issues, intensive research effort has been devoted recently to the development of passivation materials and approaches that can reduce the amount of interface and surface defect states in perovskite solar cells. Here, we have reviewed the state of the research progress in the development of passivation of different interfaces in the perovskite solar cell, including the interface (a) between transparent conductive oxide and electron transport material; (b) between the electron transport material and perovskite; (c) between the perovskite grains (grain boundaries); (d) between the perovskite and hole transport layer; (e) between the hole transport layer and electrode, and (f) between the electrode material and atmospheric environment. We also look into the prospects and challenges in the passivation of hybrid perovskite solar cells.