Designing Efficient Inverted Perovskite Solar Cells with Self-Assembled Monolayer Hole Transport Layers

Self-assembled monolayers (SAMs) have emerged as highly versatile interfacial materials in perovskite solar cells (PSCs), offering tunable molecular structures, favorable energy-level alignment, high optical transparency, and minimized non-radiative recombination losses. With the rapid advancement of inverted (p-i-n) PSC architectures, SAM-based hole-selective contacts have demonstrated distinct advantages in achieving superior power conversion efficiency, cost-effective fabrication, and strong compatibility with scalable manufacturing processes. This review first summarizes the evolution of SAM applications, with a particular focus on SAM-based materials in p-i-n PSCs. Subsequently, the fundamental aspects of SAMs are systematically discussed. Further, common preparation methods of SAMs are reviewed, along with the key challenges encountered in achieving uniform SAM coating. Based on this, recent progress in SAM-based PSCs is comprehensively summarized, including their applications in high-efficiency single-junction devices, perovskite tandem solar cells, and large-area photovoltaic modules. The crucial roles of SAMs in energy-level modulation, interfacial modification, defect passivation, and charge transport are highlighted. Finally, the remaining challenges and future prospects of SAMs in inverted PSCs are discussed, with particular emphasis on interfacial stability and long-term operational reliability. This review aims at providing systematic insights and guidance for the further development of SAM-based inverted PSCs.