Hole transport materials for scalable p-i-n perovskite solar modules

Perovskite solar cells (PSCs) have emerged as a promising avenue for sustainable energy production, offering high efficiency at a low cost. However, the commercialization of PSCs is significantly influenced by the characteristics and properties of the perovskite bottom layers. In this review, we explore the implications of the perovskite bottom layers of inverted p-i-n PSCs, specifically the hole transport layer (HTL) and the HTL/perovskite interface, which plays an important role in the commercial viability of PSCs, including the key factors such as scalability, stability, and environmental safety. We examine the scalability challenge, which is essential for moving from lab-scale prototypes to mass production, through layer uniformity and compatibility with broad-scale manufacturing techniques. Stability issues include both the operational lifespan and environmental durability of PSCs, highlighting the significance of the bottom layers in safeguarding against degradation. Furthermore, we venture into environmental safety measures, emphasizing the approaches to curtailing lead leakage via sophisticated HTL and HTL/perovskite interface engineering. Through a holistic evaluation of these pivotal aspects, this review aims to establish a blueprint for forthcoming enhancements in PSC technology, highlighting the imperative of optimizing the HTL and HTL/perovskite interface to navigate commercialization obstacles and fully explore the potential of PSCs in sustainable energy production.