Self-Assembled Monolayers as Hole-Selective Contacts in Inverted Perovskite Solar Cells: A Review

Inverted perovskite solar cells (PSCs) have gained great attention owing to their advantageous low-temperature preparation processes, high operational stability and compatibility with tandem solar cell architectures. The integration of self-assembled monolayers (SAMs) as effective hole-selective contacts in inverted PSCs has contributed to incredible advancements in device performance. In this review, we first discuss the structure and characteristics of the SAM molecules and then give an overall understanding of the bonding mechanism between SAMs and the substrate, as well as the preparation methods for SAMs. Besides, the advances of SAM-based inverted PSCs have been introduced in terms of energy band alignment and interfacial passivation and cost-effectiveness. Finally, the current issues associated with SAMs in inverted PSCs and the corresponding strategies to overcome those limitations are discussed.