The pursuit of higher power conversion efficiencies (PCEs) is a constant driving force in the development of perovskite solar cells (PSCs). While perovskites are inherently efficient light absorbers, optimizing their performance requires meticulous control over material quality and device architecture. 1,4-Phenylenediamine Dihydriodide (PDAI) has emerged as a key additive that significantly contributes to achieving higher PCEs by improving critical aspects of perovskite film formation and interface behavior.

PDAI's impact on PCE stems from its multifaceted role in enhancing perovskite film properties. Firstly, it acts as a capping agent and structural modifier, influencing the crystallization process of the perovskite layer. By facilitating the in-situ growth of a 2D perovskite interface layer, PDAI helps to passivate surface defects and minimize grain boundary density. These factors are crucial for reducing non-radiative recombination, a major loss mechanism that lowers the overall efficiency of solar cells.

Research has shown that perovskite films treated with optimal concentrations of PDAI exhibit improved crystallinity, larger grain sizes, and a more compact morphology. This enhanced structural order leads to a higher charge carrier mobility and a reduced density of charge trapping sites. When fewer charges are trapped or lost to recombination, more photogenerated carriers can be collected, directly contributing to higher short-circuit current density (Jsc) and open-circuit voltage (Voc), thereby boosting the overall PCE.

Moreover, the interface between the perovskite layer and the hole transport layer (HTL) is a critical junction where energy losses can occur. PDAI, by forming a beneficial 2D interface, can improve the energy level alignment and facilitate more efficient hole extraction. This smooth transfer of charges from the absorber to the HTL minimizes resistive losses and contributes to a higher fill factor (FF), another vital component of PCE. The synergistic effects of improved film quality and optimized interface energetics allow PDAI-treated PSCs to achieve remarkable PCEs, with studies reporting figures exceeding 16%.

The consistent enhancement in photovoltaic performance attributed to PDAI underscores its importance as a functional additive in perovskite solar cell technology. By addressing intrinsic material limitations and optimizing interfacial charge dynamics, PDAI provides a clear pathway to higher efficiency devices. As research progresses, understanding and leveraging the precise mechanisms by which PDAI boosts PCE will be key to unlocking the full commercial potential of perovskite solar cells.