Perovskite solar cells (PSCs) have emerged as a highly promising technology in the field of renewable energy, offering high power conversion efficiencies (PCEs) and low manufacturing costs. However, their widespread commercialization has been hindered by issues related to stability, particularly their susceptibility to degradation from moisture and heat. Addressing these challenges is crucial for unlocking the full potential of PSCs. In this context, innovative chemical additives are playing a pivotal role, and 1,4-Phenylenediamine Dihydriodide (PDAI) stands out as a particularly effective solution.

The core of PDAI's utility lies in its ability to act as an interface engineering agent. When introduced into the perovskite solar cell architecture, it facilitates the in-situ growth of a 2D perovskite layer at the interface between the primary 3D perovskite absorber and the hole transport layer (HTL), typically CuSCN. This strategic placement of a 2D perovskite layer has profound positive effects on the overall device performance. Scientific reports highlight that the use of PDAI leads to several key improvements: larger grain sizes in the perovskite film, more compact grain boundaries, a reduction in defect density, and consequently, more efficient charge extraction. These factors collectively contribute to a significant boost in the PCE of the solar cells.

One of the most exciting breakthroughs associated with PDAI is its contribution to the self-healing properties of PSCs. The delicate nature of perovskite materials means they can be susceptible to minor damage from environmental factors, especially moisture. PDAI-treated perovskite films have demonstrated an impressive ability to repair themselves when exposed to adverse conditions and then returned to a more favorable environment. This self-healing mechanism is attributed to the unique molecular structure of PDAI, specifically the presence of diammonium cations and an aromatic ring. These features help to stabilize the perovskite lattice, suppress ion migration, and form a more cohesive structure that can recover from degradation.

Furthermore, studies indicate that PDAI enhances the stability of PSCs against humidity and thermal stress. By passivating grain boundaries and surface defects, PDAI creates a more robust film that is less prone to decomposition. This improved durability is essential for ensuring that PSCs can withstand real-world operating conditions and maintain their performance over extended periods. The optimal concentration of PDAI has been identified as critical, with research suggesting that a specific amount maximizes these benefits without introducing adverse effects. For instance, concentrations around 5 mg mL−1 have shown optimal results, leading to PCEs as high as 16.10% and remarkable resilience.

The integration of PDAI into perovskite solar cell manufacturing represents a significant step towards developing commercially viable and long-lasting solar energy solutions. Its ability to simultaneously enhance efficiency, improve stability, and impart self-healing capabilities makes it a valuable additive for the next generation of photovoltaic technologies. As researchers continue to explore the full spectrum of its applications, PDAI is poised to play an instrumental role in the advancement of sustainable energy.