Wide-bandgap perovskite solar cells have attracted increasing attention for high-voltage photovoltaic applications, with methylammonium lead trichloride (MAPbCl₃) as a promising candidate. Nevertheless, the performance of MAPbCl₃-based solar cells remains limited by poor film quality, high defect densities, and severe non-radiative recombination losses, which limit voltage output, reproducibility, and long-term stability. While previous approaches, such as methylammonium chloride (MACl) vapor annealing, have demonstrated improved crystallinity and defect reduction, their reliance on prolonged thermal treatment raises concerns regarding scalability and process reproducibility. (1-2)
In this work, we present a phenylethylammonium chloride (PEACl) surface passivation strategy as an efficient and scalable alternative for defect passivation in MAPbCl₃ perovskite solar cells. Unlike vapor-assisted annealing methods, the PEACl treatment is implemented through a rapid, solution-based process, enabling precise interface control without extended annealing steps. This approach leads to substantial improvements in film morphology, including enhanced grain growth, stabilized grain boundaries, and a notable reduction in surface and interfacial defect states.
Comprehensive structural, optical, and electrical characterizations reveal that PEACl passivation effectively suppresses non-radiative recombination pathways and extends charge-carrier lifetimes, while maintaining the integrity of the MAPbCl₃ crystal lattice. In particular, the treatment minimizes metallic lead species at the surface and reduces halide vacancy-related trap states, resulting in improved charge extraction and reduced voltage losses. Statistical evaluation across multiple devices demonstrates that PEACl-treated solar cells exhibit significantly improved reproducibility compared to both pristine and MACl-treated counterparts, with simultaneous enhancements in open-circuit voltage, short-circuit current density, fill factor, and overall power conversion efficiency.
The performance gains are most evident in the voltage characteristics, where devices incorporating PEACl-treated MAPbCl₃ layers consistently deliver open-circuit voltages approaching 1.7 V, underscoring the effectiveness of this passivation strategy in suppressing recombination-induced voltage losses. Although MACl-treated devices can reach similar peak voltages, their response is notably less consistent, with increased variability that highlights the advantage of the PEACl-based approach. Beyond efficiency, PEACl passivation plays a decisive role in improving device stability: under ambient storage and operational conditions, PEACl-treated devices maintain stable voltage output with minimal fluctuation, while pristine and MACl-treated counterparts show pronounced instability and frequent voltage collapse, indicative of interfacial degradation. Steady-state measurements further confirm that PEACl-treated devices sustain high voltage output over extended operation times, reflecting enhanced resistance to degradation pathways. Surface wettability test supports these observations, revealing a marked increase in hydrophobicity after PEACl passivation, which implies reduced surface energy and improved resistance to moisture ingress, directly contributing to the enhanced operational stability and emphasizing the importance of surface chemistry control in wide-bandgap perovskite devices.
Overall, this study establishes PEACl surface passivation as a practical and reproducible strategy for overcoming key limitations of MAPbCl₃ perovskite solar cells. By simultaneously improving voltage performance, device uniformity, and environmental stability, this approach strengthens the prospects of wide-bandgap perovskites for next-generation photovoltaic technologies, including tandem architectures, building-integrated photovoltaics, and low-power energy applications.