Recent Progress of Hole Transport Layers of Inverted Perovskite Solar Cells

Perovskite solar cells, also known as PSCs, have become a potentially viable choice for a source of clean energy. This is especially true for the inverted structure, which boasts high stability and allows for synthesis by solution at low temperatures. In the inverse structure, one of the most important parts is called the hole transport layer, which plays a key role in acting as a substrate and transporting holes. Several studies on high-temperature liquids have been carried out as part of an effort to effectively enhance the device performance of inverted perovskite solar cells (IPSCs). In addition to common organic components, including PEDOT: PSS and PTAA, this paper also provides information regarding inorganic HTL materials, such as NiOx and compounds based on copper. This study discusses in depth the benefits and drawbacks of these four materials, as well as potential avenues for future research and development, such as the application of dopants and various interface optimization methodologies. It may be possible to improve the PCE of IPSCs as well as the stability if HTL materials are modified. This paper provides new researchers with a solid foundation and direction for optimizing HTL materials.