Two-dimensional perovskite nanomaterials, particularly Ruddlesden-Popper phases, have emerged as a promising solution to address the stability challenges of perovskite solar cells while maintaining competitive power conversion efficiencies. These materials exhibit a layered structure that combines the optoelectronic advantages of three-dimensional perovskites with enhanced environmental resilience, making them suitable for practical photovoltaic applications.

The layered structure of 2D perovskites consists of alternating inorganic sheets and bulky organic spacer cations. The inorganic layers, typically lead halide octahedra, provide the photoactive component, while the organic spacers act as insulating barriers. This arrangement creates natural quantum wells, leading to quantum confinement effects that modify the optoelectronic properties. The bandgap becomes tunable by varying the number of inorganic layers between the organic spacers, with thinner layers exhibiting larger bandgaps due to stronger confinement. This structural configuration also contributes to superior moisture resistance compared to 3D perovskites, as the hydrophobic organic spacers protect the moisture-sensitive inorganic components from degradation.

Fabrication methods for 2D perovskite nanomaterials primarily fall into two categories: solution processing and vapor deposition. Solution processing offers advantages in terms of scalability and cost-effectiveness, enabling the production of uniform thin films through spin-coating or blade-coating techniques. However, controlling the phase purity and orientation of the crystallites remains challenging, often resulting in mixed phases with varying layer numbers. Vapor deposition methods, including thermal evaporation and chemical vapor deposition, provide better control over film composition and crystallinity but require more sophisticated equipment and higher processing temperatures. Recent advances have demonstrated that hybrid approaches combining solution processing with vapor-assisted crystallization can yield high-quality 2D perovskite films with preferred vertical orientation of the layers.

The trade-off between efficiency and stability represents a critical consideration in 2D perovskite solar cell development. While 3D perovskites achieve higher efficiencies exceeding 25%, their operational stability under environmental stressors remains inadequate for commercialization. In contrast, 2D perovskites exhibit significantly improved stability, with some devices maintaining over 80% of their initial performance after 1000 hours under ambient conditions. However, the efficiency of pure 2D perovskites typically lags behind their 3D counterparts due to the insulating nature of the organic spacers that hinder charge transport. The highest efficiencies for 2D perovskite solar cells currently reach approximately 18%, demonstrating the need for further optimization.

Several strategies have been developed to optimize charge transport in 2D perovskite nanomaterials. Engineering the orientation of the quantum wells to facilitate vertical charge transport has proven effective, achieved through solvent engineering or additive-assisted crystallization. Compositional engineering, particularly through the incorporation of mixed cations and halides, can reduce the exciton binding energy and improve charge separation. Interface engineering between the 2D perovskite and charge transport layers minimizes recombination losses, while dimensionality tuning through the introduction of quasi-2D structures with varying layer thicknesses helps balance stability and efficiency.

Quasi-2D perovskites represent a significant recent advancement, combining multiple perovskite layer thicknesses within a single material. These structures create energy funneling effects that direct excitons toward the lower-bandgap regions, improving charge collection efficiency. The gradient composition in quasi-2D perovskites also passivates defects and reduces non-radiative recombination, leading to enhanced open-circuit voltages. Recent studies have demonstrated quasi-2D perovskite solar cells with efficiencies approaching 20% while maintaining excellent stability, representing a promising compromise between performance and reliability.

Commercialization potential for 2D perovskite solar cells appears promising due to their inherent stability advantages and compatibility with existing photovoltaic manufacturing processes. The materials demonstrate improved resistance not only to moisture but also to heat and light-induced degradation, critical factors for real-world operation. Industrial-scale production feasibility has been demonstrated through roll-to-roll processing trials, with prototype modules showing consistent performance over extended periods. The ability to tune the bandgap through layer number engineering also makes 2D perovskites attractive for tandem solar cell applications, where they can be combined with silicon or other perovskite compositions to surpass single-junction efficiency limits.

Ongoing research focuses on further improving the performance of 2D perovskite solar cells while maintaining their stability advantages. Efforts include developing new organic spacer molecules that reduce the insulating barrier while preserving the protective function, optimizing the crystallization process to control phase distribution, and engineering device architectures to minimize interfacial losses. The combination of these approaches continues to narrow the performance gap with 3D perovskites while offering substantially improved reliability.

The environmental stability of 2D perovskites also addresses concerns regarding lead leakage, a critical issue for perovskite photovoltaic technology. The layered structure effectively encapsulates the lead-containing inorganic sheets, significantly reducing the risk of environmental contamination compared to 3D perovskites. This feature, combined with the potential for lead reduction or replacement through compositional engineering, improves the sustainability profile of the technology.

As the field progresses, standardization of stability testing protocols will be crucial for accurate performance comparisons between different 2D perovskite formulations. Current research employs various accelerated aging tests under different environmental conditions, making direct comparisons challenging. The development of industry-wide stability metrics specific to 2D perovskites will facilitate technology transfer from laboratory-scale devices to commercial products.

The unique properties of 2D perovskite nanomaterials position them as strong candidates for next-generation photovoltaic technology. Their combination of tunable optoelectronic properties, environmental stability, and processing versatility addresses many of the limitations that have hindered the commercialization of conventional perovskite solar cells. Continued advancements in material design and device engineering are expected to further improve their performance while maintaining the inherent stability advantages, potentially enabling widespread adoption in the solar energy market.