The research centers on a novel co-crystal engineering strategy, leveraging the unique properties of benzoguanamine—a neutral molecule seldom explored in perovskite chemistry—as a linker within low-dimensional perovskites. Traditional methods typically utilize ionic molecules to form these 2D layers; however, these ionic components can contribute to instability through ion migration and environmental degradation. By replacing these conventional ionic linkers with benzoguanamine, researchers have forged a co-crystal structure that not only sustains high photovoltaic performance but also significantly bolsters the operational stability of the devices.

Applying this co-crystal interlayer onto the perovskite active layer facilitates exceptional power conversion efficiencies (PCEs) that rival, if not surpass, those achieved with standard 2D perovskite structures. Specifically, small-area solar cells fabricated with this co-crystal engineering approach have demonstrated outstanding PCEs of 23.4%. Beyond the laboratory-scale devices, the researchers successfully scaled the technology to solar modules with active areas measuring 9.0 cm² and 48 cm², which achieved PCEs of 23.1% and 18.5%, respectively. These figures mark a significant stride towards the practical deployment of high-performance perovskite solar modules in real-world applications.

What sets this development apart is not only the impressive efficiency but the unprecedented operational stability exhibited by these co-crystal engineered modules. The solar modules retained more than 95% of their initial efficiency following over 5,000 hours of continuous one-sun light soaking at maximum power point conditions—a stress test that simulates extended exposure to sunlight under real operating conditions. Moreover, when subjected to ultraviolet (UV) radiation exposure exceeding 1,000 hours, the modules maintained over 98% of their initial efficiency, highlighting their robustness against UV-induced degradation mechanisms, which are typically detrimental to perovskite materials.

Thermal stability, another critical parameter for photovoltaics especially in harsh climates, has also been markedly improved by this co-crystal approach. Under continuous thermal stress at 85°C for more than 5,000 hours, the solar modules retained over 91% of their initial efficiency. This level of heat endurance is a transformative milestone, illustrating that the molecular design within the 2D perovskite interlayers can fundamentally enhance the structural and chemical stability of the entire device.

The success of this work is rooted in the careful molecular engineering of the perovskite interface. Benzoguanamine, being a neutral molecule, forms strong hydrogen bonding and van der Waals interactions within the co-crystal network. This contrasts markedly with ionic molecules whose interactions may be more prone to disruption via environmental factors like moisture and thermal fluctuations. As a result, the benzoguanamine-based co-crystal provides a stable scaffold that inhibits ion migration—a well-known degradation pathway in perovskite solar cells—thus preserving the integrity of the perovskite lattice over extended operation.

Fundamental photophysical characterizations demonstrate that the presence of the benzoguanamine linker does not hinder but rather optimizes charge transport across the interlayer. This is paramount because maintaining efficient charge extraction is essential for retaining high photovoltaic efficiency. The co-crystal engineered interlayer ensures a seamless electronic interface between the perovskite absorber and transport layers, minimizing recombination losses and promoting sustained device performance.

This pioneering technique signals a paradigm shift in the design principles for perovskite solar cells. Instead of merely focusing on the perovskite absorber composition or device encapsulation to boost stability, this approach innovates at the molecular scale by tailoring the chemistry of the interlayer itself. It bridges the gap between efficiency and stability—a trade-off that has long hampered perovskite solar technology—and effectively rewrites the roadmap toward commercial viability.

Scaling up from lab-scale cells to larger modules often results in performance penalties due to inhomogeneities and defect states; however, the co-crystal interlayer appears to alleviate these issues. The solar modules fabricated show minimal efficiency loss compared to their smaller counterparts, demonstrating the robustness and uniformity of the co-crystal layer deposition. This scalability is a crucial step toward integrating perovskite solar modules into the existing photovoltaic market.

The resilience to prolonged UV exposure is particularly noteworthy, as UV damage can generate trap states and catalyze chemical degradation within the perovskite lattice. The neutral molecular framework of the co-crystal likely imparts a UV-filtering or UV-resilient quality to the interlayer, protecting the underlying perovskite from photochemical deterioration and thereby extending device lifetime.

Moreover, the thermal endurance achieved suggests that the co-crystal interlayer can counteract thermal expansion mismatches between the perovskite and adjacent layers, a common issue that leads to mechanical failure and interface delamination. This implies that the benzoguanamine-based co-crystal forms a mechanically robust and thermally stable interface that can withstand the thermal cycling conditions typical in outdoor environments.

In essence, this study embodies a synthesis of chemistry, materials science, and device engineering to address the critical challenges that have limited the widespread adoption of perovskite solar technologies. By unlocking the potential of neutral molecule-based co-crystals, the work propels the field toward sustainable, efficient, and durable solar energy solutions.

Looking ahead, the implications of this research extend beyond photovoltaics. The co-crystal engineering approach may inspire analogous strategies in other optoelectronic devices where stability and performance are paramount, including light-emitting diodes, photodetectors, and sensors. The molecular design principles elucidated here could become a universal toolkit for crafting next-generation materials with tailored functionalities.

This breakthrough was achieved through a multidisciplinary collaboration combining synthetic chemistry, advanced materials characterization, device fabrication, and longevity testing. These collective efforts underscore the critical importance of integrating diverse scientific disciplines to overcome entrenched technical roadblocks.

Ultimately, the research exemplifies how fundamental molecular manipulation can translate directly into tangible technological advancements, offering a compelling vision for the future of solar energy that is both highly efficient and reliably stable under real-world conditions. It paves the way for perovskite solar modules to transition from laboratory curiosities to commercially entrenched clean energy solutions.

As the world grapples with the urgent need to transition to renewable energy, innovations such as this co-crystal engineering strategy provide a beacon of hope. They illustrate how meticulous molecular engineering can solve practical challenges, enabling perovskite solar cells to meet their promise as a cornerstone of global sustainable energy infrastructures.

Subject of Research:
Perovskite solar cells and interfacial engineering to enhance efficiency and stability

Article Title:
Co-crystal engineering of a two-dimensional perovskite phase for perovskite solar modules with improved efficiency and stability

Article References:
Yaghoobi Nia, N., Zendehdel, M., Paci, B. et al. Co-crystal engineering of a two-dimensional perovskite phase for perovskite solar modules with improved efficiency and stability. Nat Energy (2025). https://doi.org/10.1038/s41560-025-01903-9

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s41560-025-01903-9

Keywords:
Perovskite solar cells, two-dimensional perovskites, co-crystal engineering, benzoguanamine, photovoltaic efficiency, operational stability, ultraviolet stability, thermal stability, power conversion efficiency, interface engineering

Perovskite solar cells have captivated the scientific and engineering communities due to their exceptional photovoltaic properties paired with cost-effective manufacturing possibilities. However, despite rapid improvements over the past decade, the interface between the perovskite layer and the electron transport layer often remains a significant bottleneck. This “buried interface” harbors complex defects and suffers from mechanical stresses that detrimentally impact device efficiency and longevity. Unmitigated, these factors throttle carrier extraction and accelerate device degradation, representing a major hurdle to PSC commercialization.

The research team has introduced a novel self-regulating “bilateral anchoring” molecular design centered around squaric acid (SA), a unique four-membered cyclic compound featuring dual carboxylic acid groups. This molecular bridge promotes robust bonding on both sides of the interface: it forms strong hydrogen bonds with the tin oxide (SnO₂) electron transport layer while simultaneously coordinating with under-coordinated lead ions (Pb²⁺) within the perovskite layer. This one-molecule solution elegantly fortifies the interface against the physical and chemical instabilities that traditionally plague PSCs.

Critically, the SA molecule exhibits a self-transforming quasi-aromatic backbone that dynamically responds to thermal processing. Prior to treatment, PSCs endure residual tensile stresses upwards of 24.6 MPa, which predispose the perovskite lattice to microcrack formation upon heating or mechanical deformation. Remarkably, the adoption of SA converts these detrimental tensile forces into beneficial compressive stress, reaching approximately -17 MPa. This stress reversal not only preserves the structural integrity of the perovskite film but also significantly enhances durability under thermal cycling and prolonged operation.

Furthermore, detailed density functional theory (DFT) simulations conducted by the team reveal substantial increases in the formation energies of common perovskite defects such as formamidinium vacancies (V FA), iodide vacancies (V I), lead vacancies (V Pb), and oxygen vacancies (V O) upon SA bonding. This indicates an effective passivation of trap states, which translates to a dramatic reduction in nonradiative recombination losses within the device. Complementing this, space-charge-limited current (SCLC) measurements indicate the charge-carrier mobility in SA-modified perovskites nearly doubles, climbing from 3.22 × 10⁻³ to 5.88 × 10⁻³ cm² V⁻¹ s⁻¹, directly contributing to enhanced photovoltaic performance.

The practical impact of this molecular engineering is persuasive. PSCs incorporating the SA interlayer achieve record power conversion efficiencies (PCEs) of 25.50% for rigid devices and 24.92% for flexible variants, both demonstrating markedly reduced hysteresis effects. These performances not only rival but also surpass many existing PSC benchmarks, particularly considering the modest hysteresis values below 2%, which indicate stable and reliable charge extraction behavior.

Strengthening the case for commercial viability, the technique exhibits broad compatibility with industrial-scale deposition methods, including spin coating, blade coating, and slot-die coating on diverse substrates such as glass, polyethylene naphthalate (PEN), and stainless steel foils. This compatibility addresses a critical scalability challenge that often impedes the transition from laboratory-scale to pilot-line manufacturing. Notably, 1 cm² rigid perovskite modules fabricated using this method maintain impressive efficiencies exceeding 24%, signaling tangible progress toward large-area device integration.

Crucially, long-term stability tests underscore the robustness engendered by the SA interlayer. Unencapsulated perovskite films retain more than 90% of peak power output even after over 3,800 hours exposed to moderate humidity (45 ± 5% RH). Thermal aging at 85 °C for 528 hours results in only a minor 12% decline in efficiency, while continuous one-sun maximum power point tracking over 1,700 hours preserves approximately 88% of initial device performance. Flexible devices subjected to rigorous mechanical flexing endure 10,000 bending cycles at a 5 mm radius with less than 10% capacity loss, an achievement underscoring their potential for wearable and portable energy harvesting applications.

The researchers emphasize that the success of this self-regulated bilateral anchoring strategy not only stems from its defect passivation prowess but also its intrinsic ability to manage interfacial mechanical stresses—two fundamental challenges that previously limited the durability and efficacy of PSCs. By uniting these functionalities in a single-component molecule, they pave the way for future solar cells exhibiting both excellent power output and longevity under real-world conditions.

Anticipating the next stages of development, the research team is actively coordinating the translation of the SA interface modification technique to roll-to-roll manufacturing lines catering to flexible PEN substrates. Mini-module production at dimensions approaching 30 × 30 cm² has already commenced, and efforts are underway to secure IEC 61215 certification within two years, which would signify compliance with international reliability and safety standards for photovoltaic modules.

In the broader context of renewable energy innovation, this landmark work elevates squaric acid as a commercially viable, multifunctional interface engineering molecule that seamlessly integrates charge transport enhancement, defect passivation, stress alleviation, and compatibility with various fabrication techniques. It presents a compelling blueprint for achieving scaled-up, efficient, and stable perovskite photovoltaics, a critical leap toward widespread solar energy adoption.

Ultimately, the team’s contributions propel PSCs closer toward the coveted promise of affordable, high-performance solar technology ubiquitously deployable across diverse substrates and environments. The convergence of molecular design insight with practical engineering solutions exemplifies how interdisciplinary ingenuity catalyzes transformative advances in next-generation photovoltaics. The scientific community eagerly awaits forthcoming pilot-line results expected from the collaborative laboratories of Professors Liu, Zhang, and Pan, heralding a new dawn for durable, efficient, and flexible perovskite solar cells.

Subject of Research: Perovskite Solar Cells, Interface Engineering, Molecular Passivation

Article Title: Self-Regulated Bilateral Anchoring Enables Efficient Charge Transport Pathways for High-Performance Rigid and Flexible Perovskite Solar Cells

News Publication Date: 14-Jul-2025

Web References: 10.1007/s40820-025-01846-6

Image Credits: Haiying Zheng, Guozhen Liu, Xinhe Dong, Feifan Chen, Chao Wang, Hongbo Yu, Zhihua Zhang, Xu Pan

Keywords: Perovskite Solar Cells, Interface Engineering, Squaric Acid, Charge Transport, Defect Passivation, Mechanical Stress Management, Flexible Photovoltaics, Photovoltaic Stability

Perovskite solar cells have rapidly climbed to the forefront of photovoltaic research over the past decade due to their remarkable potential for high efficiency and low-cost manufacturing. Despite their promise, these cells historically struggled with issues pertaining to operational stability and longevity, hindering widescale commercialization. The NIMS Award-winning research directly addresses these bottlenecks by introducing a crucial innovation—the solid-state hole transport layer. This component has significantly enhanced both the stability and photoelectric conversion efficiency of perovskite solar cells, marking a transformative step toward their real-world viability.

The integration of the solid-state hole transport layer represents more than a mere incremental improvement; it is a quantum leap in device architecture. By replacing traditional liquid electrolytes, which were prone to degradation and leakage issues, with a solid material layer, the perovskite solar cells now exhibit increased durability under environmental stresses such as moisture and heat. Moreover, this innovation facilitates better charge extraction and transport within the cell, reducing energy losses that previously limited device efficiency.

Technically, the hole transport layer functions by selectively transporting positive charge carriers (holes) from the perovskite absorber to the electrode, ensuring minimal recombination losses while maintaining electrical insulation from the electron-collecting layer. This selective transport is vital because any inefficiency at this interface reduces the overall photocurrent and, subsequently, the power conversion efficiency of the solar cell. The awardees’ contributions effectively stabilized this interface, mitigating hysteresis effects and boosting long-term operational stability—key parameters for real-world application.

What makes this collaborative breakthrough exceptionally noteworthy is its global scale of impact. The independent but synergistic efforts of Miyasaka, Snaith, and Park not only pioneered the application of solid-state hole transport materials but also laid the experimental and theoretical foundations that many research groups worldwide have built upon. Their work bridged the gap between laboratory-scale high efficiencies and scalable, durable devices poised for commercialization.

Beyond the scientific rigor, this achievement aligns seamlessly with the broader imperative of creating sustainable energy technologies. Perovskite solar cells offer a pathway toward affordable, lightweight, and flexible photovoltaics that can be deployed in diverse environments—ranging from urban rooftops to portable electronics. The improved stability fosters confidence among investors and manufacturers, potentially catalyzing mass production models that could accelerate the global transition to clean energy sources.

The NIMS Award ceremony and associated symposium will convene at the Tsukuba International Congress Center on November 11th, 2025. This gathering promises a platform not only for celebrating these remarkable scientific accomplishments but also for fostering dialogue among materials scientists, photovoltaic engineers, and policy makers. The symposium will include detailed lectures given by the awardees themselves, invited talks from leading researchers, and presentations that highlight complementary advancements within the field of energy-related materials.

The international stature of the NIMS Award reflects its stringent selection process, which evaluates groundbreaking contributions from four major subdivisions of materials science: environmental and energy materials, functional materials, structural materials, and basic materials science. Its thematic approach each year ensures that impactful research with real-world applications is prioritized, further emphasizing the role of materials science in addressing pressing technological and societal challenges. For 2025, the spotlight on energy materials underscores the urgent global necessity to innovate sustainable energy technologies.

The recognition of perovskite solar cell innovation by a leading institution like NIMS also highlights the importance of cross-border scientific collaboration. The honorees hail from prominent institutions in Japan, the United Kingdom, and South Korea respectively, underscoring the collaborative nature of contemporary materials science research. Their combined efforts exemplify how diverse academic cultures and expertise can converge to solve some of the most daunting technological problems.

Looking forward, the developments recognized by the NIMS Award will likely stimulate further research into alternative materials and device architectures that enhance photovoltaic performance. This includes exploring new solid-state hole transport materials with better electronic properties, improving perovskite crystallinity and interface engineering, and integrating these cells into tandem configurations for surpassing traditional silicon-based solar cell efficiency limits.

Moreover, from an industrial perspective, the stabilization of perovskite solar cells opens the door for their incorporation into building-integrated photovoltaics (BIPV), wearable electronics, and even aerospace applications, where weight and flexibility are paramount. These applications have the potential to revolutionize how solar energy is harvested and utilized, moving beyond the constraints of traditional rigid panels.

The NIMS Award 2025 thus not only celebrates an exceptional scientific breakthrough but also symbolizes a critical inflection point in the journey toward sustainable energy futures. It honors the dedication and ingenuity of researchers who have translated fundamental materials science insights into transformative technologies. Their work foreshadows a future where clean, efficient, and affordable solar energy is universally accessible, contributing meaningfully to reducing global carbon emissions and combating climate change.

As the world watches the upcoming award symposium, anticipation builds regarding the new research directions and collaborations that this recognition might inspire. The dissemination of knowledge through such prestigious events helps cultivate a vibrant scientific community and accelerates the translation of innovative materials research into solutions that tackle humanity’s greatest challenges.

In summary, the 2025 NIMS Award highlights essential advancements in perovskite solar cell technology, emphasizing the integration of the solid-state hole transport layer. This advancement addresses longstanding issues of stability and efficiency, enabling practical application potentials for perovskite photovoltaics. By honoring Prof. Miyasaka, Prof. Snaith, and Prof. Park, NIMS acknowledges not only their individual excellence but also the enduring global impact of their collaborative scientific achievements.

Subject of Research: Advances in perovskite solar cell technology focusing on stability and efficiency through solid-state hole transport layers.

Article Title: Global Breakthrough in Perovskite Solar Cells Earns NIMS Award 2025 for Pioneering Researchers

News Publication Date: Not specified in the original content.

Image Credits: NIMS (National Institute for Materials Science)

Keywords

Perovskite solar cells, solid-state hole transport layer, photoelectric conversion efficiency, stability, renewable energy, photovoltaic technology, materials science, NIMS Award, sustainable energy, environmental materials, energy materials, solar photovoltaic innovation