PTAA as Efficient Hole Transport Materials in Perovskite Solar Cells: A Review

Perovskite solar cells (PSCs) with a power conversion efficiency (PCE) over-passing 25% have proved to be the most promising competitor for the next-generation photovoltaic technology. Massive efforts are devoted to the improvement of the performance and stability of PSCs, whereas the hole transport layer (HTL) has attracted significant interest. Among diverse hole transport materials, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) is one of the most promising candidates due to its ease of fabrication, transparency to visible light, mechanical flexibility, conductivity, and stability. Over the past few years, there has been an increasing amount of research using PTAA as the HTL first in n-i-p and then in p-i-n PSCs with extended applications in flexible, large-area, and tandem devices. Herein, a progress review on PTAA for PSC applications is provided, which enables a better understanding of the advantages and disadvantages of PTAA, as well as the approaches to fully realizing its tremendous potential. The emerging and promising research directions for PTAA-based PSCs are discussed, shedding light on the practical applications of PTAA.