The field of perovskite solar cells has witnessed remarkable advances in recent years, with formamidinium and caesium metal halide perovskites standing out as leading materials for achieving high photovoltaic efficiencies. Despite their promise, a persistent challenge has been the uncontrolled crystallization of these materials, which hampers their performance and long-term stability. Today, a groundbreaking study illuminates a novel strategy to overcome these hurdles by harnessing the power of aromatic molecular interactions, thereby paving the way for perovskite solar cells with unprecedented efficiency and durability.
Central to this transformative approach is the regulation of perovskite nucleation and growth via carefully engineered aromatic interactions. The research team employed naphthalene-based molecular salts, specifically naphthalene ammonium salts and naphthalenesulfonates, to steer the crystallization process with exquisite precision. Unlike traditional methods that rely primarily on solvent engineering or additive incorporation, this chemical strategy exploits the unique ability of naphthalene moieties to engage in strong aromatic stacking interactions. Such interactions are positioned adjacently to the pivotal [PbI_6]^4− octahedra critical for the perovskite crystal framework.
This innovative molecular design fosters ordered out-of-plane crystallization along the (100) crystallographic plane, a facet of crystallinity that significantly impacts charge transport and defect density. The ammonium groups of these naphthalene compounds effectively substitute at the formamidinium sites within the perovskite lattice, while the sulfonate groups engage directly with lead ions, thereby establishing a dual role in both lattice incorporation and defect passivation. The synergy of these interactions serves to mitigate common perovskite defects, reduce trap states, and enhance carrier mobility—factors essential for optimizing photovoltaic conversion efficiency.
The experimental results from applying this strategy are staggering. The fabricated inverted perovskite solar cells demonstrated a power conversion efficiency (PCE) of 27.02%, with certification confirming an efficiency of 26.88%. This efficiency level not only surpasses many prior benchmarks but also positions inverted architecture solar cells competitively against more conventional n-i-p configurations. Beyond efficiency, these devices displayed exceptional operational stability; encapsulated devices retained 98.2% of their initial performance after continuous maximum power point tracking for 2000 hours under full illumination in ambient air conditions—a critical validation of their practical viability.
Beyond single cells, the implications of this aromatic interaction-driven crystallization extend to much larger scales. The research team successfully translated this molecular engineering approach to inverted mini-modules, achieving a certified steady-state efficiency of 23.18% over an aperture area exceeding 11 square centimeters. Such scalability is vital for industrialization prospects and real-world solar energy applications. Moreover, the technique propelled all-perovskite tandem solar cells to a certified efficiency of 29.07%, highlighting its versatility across diverse device configurations and underscoring the approach’s potential to drive next-generation photovoltaic technologies.
Delving deeper into the mechanistic aspects, the aromatic stacking between naphthalene moieties controls crystal orientation perpendicular to the substrate, thereby aligning the perovskite grains strategically for efficient charge extraction. The (100) plane orientation presents a low-energy pathway for carriers, enabling electrons and holes to travel with minimal recombination losses. This ordered out-of-plane growth contrasts sharply with the often random and disordered orientations found in untreated perovskite films, which typically suffer from increased defect-induced charge traps and suboptimal transport pathways.
Moreover, the dual-functionality of the naphthalene ammonium and sulfonate groups not only dictates crystal growth patterns but also serves to chemically passivate surfaces and grain boundaries. This passivation reduces carrier recombination by neutralizing defect sites that would otherwise act as non-radiative recombination centers. The improved interface chemistry and crystallography collectively contribute to the enhancements in both efficiency and longevity observed across the study’s devices.
From a materials chemistry perspective, the choice of naphthalene as the aromatic system is highly insightful. Its planar structure and robust π–π stacking interactions provide a stable platform that influences perovskite crystallization at the molecular level. This approach signifies a shift from the conventional focus on ionic or purely electronic effects within perovskite systems to exploiting supramolecular chemistry and non-covalent interactions as precise levers for materials engineering.
The implications of this study ripple across multiple scientific and technological domains. In photovoltaic research, it offers a new paradigm for material design that couples crystallographic control with chemical passivation through aromatic interactions. For the solar energy industry, these findings open pathways to manufacturing highly efficient, stable, and scalable perovskite solar modules that could significantly disrupt the current energy market. Moreover, the methodologies developed here can inspire analogous strategies in other optoelectronic devices where crystallinity and defect control are pivotal.
Furthermore, the impressive stability metrics achieved under continuous illumination in ambient air are particularly revelatory. Stability remains the Achilles’ heel for many perovskite technologies, and long-term performance retention has often lagged behind efficiency improvements. By stabilizing the perovskite microstructure via aromatic interactions, this method directly addresses degradation pathways and enhances resilience against environmental stressors—crucial for commercial deployment.
The demonstration of all-perovskite tandem solar cells attaining nearly 30% efficiency underscores the technique’s transformative potential in multi-junction architectures. Tandem cells leverage the complementary absorption properties of stacked layers, demanding precisely engineered interfaces and structural coherence. The aromatic interaction strategy’s ability to induce organized crystallization likely improves the electronic coupling between subcells, maximizing overall device performance.
Integrating these insights into future research could expand the scope of aromatic molecular engineering to other metal halide perovskite compositions, such as those incorporating mixed halides or alternative cations. Exploring different aromatic frameworks with tunable electronic and steric properties might further optimize crystal growth and defect passivation processes. Additionally, pairing this molecular approach with complementary fabrication techniques could yield even higher efficiencies and stability benchmarks.
This work also prompts a reconsideration of how subtle molecular forces can be harnessed within thin-film semiconductors. Aromatic π–π interactions have long been studied in organic electronics but remain underexploited in the context of inorganic-organic hybrid frameworks like perovskites. The bridging of these scientific disciplines could spawn novel hybrid materials with tailored optoelectronic properties and unprecedented functional complexity.
Ultimately, the successful coupling of aromatic molecular chemistry and perovskite crystallography demonstrated in this study heralds a disruptive leap forward for solar energy technology. It exemplifies how molecular-level understanding and design can translate into tangible improvements in device performance and stability, inching closer toward the long-sought goal of low-cost, efficient, and sustainable photovoltaic solutions.
With energy demands escalating and climate imperatives intensifying, breakthroughs like this provide crucial momentum for renewable energy development worldwide. The elegantly simple yet profoundly impactful concept of aromatic interaction-driven crystallization could be the key to unlocking the full potential of perovskites, driving the next generation of solar cells into the commercial spotlight and beyond.
Subject of Research: Perovskite solar cells, aromatic interaction-driven crystallization, defect passivation, photovoltaic efficiency improvement.
Article Title: Aromatic interaction-driven out-of-plane orientation for inverted perovskite solar cells with improved efficiency.
Article References:
Zhou, Q., Huang, G., Wang, J. et al. Aromatic interaction-driven out-of-plane orientation for inverted perovskite solar cells with improved efficiency. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01882-x
Image Credits: AI Generated
