Perovskites are a family of crystalline materials whose electronic properties can be tuned through their chemical composition. In solar cells, they absorb sunlight efficiently and generate mobile charge carriers, making them attractive for lightweight, flexible and potentially low-cost photovoltaic technologies. Screen printing could make these devices especially scalable because it deposits functional materials through patterned meshes, much like industrial printing processes. In a fully screen-printed architecture, multiple layers can be deposited sequentially, including the charge-transporting components, the perovskite absorber and the carbon electrode. The approach reduces reliance on vacuum equipment and could simplify manufacturing. But thick printed layers create a difficult physical environment for crystallization. A precursor solution must penetrate downward through the porous structure, react and solidify in the correct sequence, and form a continuous semiconductor without leaving voids, defects or mechanical stress behind.

The researchers identify inefficient vertical phase transformation as a central obstacle. During fabrication, the liquid perovskite precursor must undergo a transition from a solution containing dissolved and dispersed chemical components into an ordered crystalline solid. If crystallization begins too early at the surface, a crust can form before the underlying material has been fully infiltrated. That premature surface nucleation blocks further penetration and leaves the lower portions of the film poorly converted. Incomplete infiltration can create disconnected regions, while uneven crystallization generates defects that trap charge carriers. Residual stress may also accumulate as the material shrinks or rearranges during solidification. Each of these problems can reduce the current extracted from the cell and increase recombination, a process in which electrons and holes meet before they can do useful work in an external circuit. In thick printed films, controlling the path and timing of the liquid is therefore as important as controlling the final crystal chemistry.

To address the problem, the team developed what it calls a fluid motion crystallization strategy. The method uses a co-solvent system composed of the ionic liquid methylammonium propionate and butyronitrile. Ionic liquids are salts that remain liquid under relatively mild conditions and can strongly interact with precursor species, while butyronitrile is used here to alter how the precursor solution flows and solvates its ingredients. According to the study, butyronitrile reduces the resistance to fluid motion and helps disperse aggregates of lead iodide, a key precursor component. The result is an optimized solvation structure: rather than allowing large or poorly dispersed precursor clusters to impede movement, the liquid remains sufficiently mobile to travel rapidly and deeply into the printed film. This fluid-control step is crucial because it shifts crystallization from a surface-dominated event to a more coordinated transformation throughout the film’s depth.

The proposed mechanism begins with rapid, deep infiltration of the precursor into the multilayered structure. Once the liquid has reached the lower regions, the material undergoes a bottom-up, ordered phase transition. In practical terms, crystallization starts in the interior or lower portion of the film and progresses upward before a competing crystalline layer can form at the exposed surface. This sequence helps the entire precursor volume participate in the conversion, reducing the likelihood of unfilled pockets and poorly connected grains. It also suppresses the formation of defects associated with abrupt or incomplete solidification. The importance of this ordering lies in the fact that a solar-cell absorber is not simply a layer of light-absorbing material; it must also provide a continuous route for photogenerated charges to reach the electrodes. A film that appears visually complete can still contain microscopic barriers that cause electrical losses if its crystals are poorly connected or riddled with defect sites.

After the controlled phase transition, the researchers observed the growth of a dense, interconnected network of perovskite nanocrystals. Nanocrystals are crystalline domains measured on the nanometre scale, and their connectivity determines how efficiently charges can move through the absorber. The reported network is accompanied by an island-like surface morphology rather than an entirely flat interface. That morphology strengthens contact between the perovskite and the carbon electrode deposited above it. The interface is a critical region in a printed solar cell: photogenerated electrons and holes must be transferred across it without becoming trapped or recombining. Intimate physical contact can lower interfacial resistance and provide more direct pathways for charge extraction. By combining a compact internal crystal network with a better-connected surface, the strategy appears to address two linked sources of loss—poor transport through the absorber and recombination near the electrode boundary.

The performance figures suggest that the processing method does more than improve an isolated laboratory measurement. The air-processed, fully screen-printed cells reached 22.41% power conversion efficiency, meaning that fraction of incident solar power was converted into electrical power under the reported testing conditions. The certified value of 21.86% is particularly significant because certification provides an independent assessment of the device’s measured output. Efficiency alone, however, is an incomplete measure of photovoltaic progress. Perovskite materials have historically faced concerns over long-term stability, with heat, light, moisture and electrical operation all capable of accelerating degradation. In this study, the devices preserved over 90.5% of their starting efficiency after 2,000 hours under ISOS-L-1 accelerated light-soaking conditions. They also showed no degradation after 900 hours at 85 °C and 50% ± 10% relative humidity under the ISOS-L-3 operational protocol, combining elevated temperature, moisture and continuous operation.

Those durability results are closely connected to the film’s microscopic structure. Defects and voids can act as chemical and electrical weak points, allowing moisture or heat to trigger local deterioration and creating pathways for further damage. Residual stress can have a similar effect by making the film more vulnerable to cracking or interfacial failure during thermal cycling. A dense, interconnected nanocrystal network may limit these vulnerabilities, while stronger contact with the carbon electrode can help preserve the electrical connection as the device operates. The study does not present stability as a separate coating or after-treatment solution; instead, it links durability to how the precursor flows and crystallizes during fabrication. That is an important shift in emphasis. Controlling the earliest stages of film formation may prevent the structural imperfections that later become visible as efficiency losses, rather than attempting to repair them after the solar cell has already been built.

The work also illustrates why manufacturing physics can determine whether an emerging photovoltaic technology remains a laboratory curiosity or becomes an industrial contender. Perovskite absorbers can be deposited at relatively low temperatures and are compatible with solution-based processing, but those advantages are realized only if the liquid precursor can be controlled across large areas and through multiple layers. Screen printing offers a potentially high-throughput route, yet its patterned deposition process naturally creates films whose thickness and porosity must be managed during conversion. A co-solvent that tunes fluid resistance, precursor aggregation and the order of crystallization could therefore be valuable beyond the specific devices tested in this study. The reported approach is not merely an adjustment to the final electrode or a small optimization of a laboratory coating; it targets the coupled relationship between fluid dynamics, chemical solvation, nucleation and charge transport. That integrated control is what makes the result potentially relevant to scalable production.

The researchers’ results do not eliminate every challenge facing perovskite solar technology, and the reported tests do not by themselves establish how the cells would perform over many years outdoors or across industrial-scale modules. Nevertheless, the combination of air processing, full screen printing, certified efficiency above 21%, and strong resistance to demanding light, heat and humidity tests gives the strategy unusual news value. The core insight is both technically specific and broadly understandable: in a thick printed solar cell, the route taken by a liquid before it becomes a crystal can determine how well the finished device works. By making the precursor more mobile, dispersing lead iodide aggregates and forcing crystallization to proceed from the bottom upward, the team created a more continuous absorber and a more effective carbon interface. The result is a perovskite solar cell designed not only to capture sunlight efficiently, but also to survive the physical stresses imposed by practical operation.

The core challenge limiting perovskite solar cells (PSCs) is the prevalence of defects within their crystalline lattice. These defects act as trap sites for charge carriers, severely impeding their mobility and thus diminishing device performance. Moreover, the ions within these materials tend to migrate, especially under operational stress, accelerating degradation. Understanding and controlling these molecular phenomena have become paramount to push the technology from laboratory curiosity to commercial viability. The IPC PAS research team, collaborating with experts from the University of Wrocław, has engineered a groundbreaking 2-in-1 molecular strategy that simultaneously addresses defect passivation and ion migration suppression.

At the heart of this innovation is a custom-designed meso-crowned porphyrin-based compound, called [12]-C-4POR, which synergistically functions as a molecular “umbrella”. Porphyrins themselves are renowned for their ability to bind metal ions and influence electronic properties beneficially within perovskite architectures. However, [12]-C-4POR takes this capability to an advanced level by incorporating crown ether moieties into the aromatic porphyrin core. This dual-cavity structure can selectively trap two types of crucial ions: lead (Pb^2+) and lithium (Li^+). The porphyrin core strongly coordinates with lead ions, passivating surface defects that otherwise act as non-radiative recombination centers. Simultaneously, the crown ether component entraps lithium ions, curtailing their mobility within the perovskite matrix, a known contributor to ion migration and device instability.

By engineering the material at this molecular scale, the researchers have achieved a profound reduction in structural defects and drastically suppressed ion movement. The impact on the solar cell’s electronic dynamics is striking: treated perovskite films exhibited reduced surface trap density and minimized nonradiative recombination. These improvements translate to a power conversion efficiency (PCE) of 23.14%, surpassing untreated cells that reached a maximum of 21.6%. This leap not only marks a new efficiency milestone but also demonstrates the effect of precise molecular engineering on photovoltaic performance.

Yet, efficiency gains mean little without addressing the operational stability of perovskite cells under environmental stressors such as heat, light, and moisture. This is where the molecular umbrella analogy holds even more relevance. Besides defect passivation and ion trapping, [12]-C-4POR enhances the hydrophobic nature of the perovskite layer, thereby creating a barrier against moisture ingress—a leading cause of material degradation. The molecular hydrophobicity reduces water-induced lattice disruption, extending the lifespan of the solar cell.

Long-term stability tests brought the most compelling evidence of the compound’s efficacy. After continuous operation spanning 800 hours, solar cells treated with [12]-C-4POR retained approximately 95% of their original efficiency, whereas the untreated control devices lost nearly half their performance, dropping to around 55%. This stark contrast confirms that the molecular strategy does not merely delay degradation but fundamentally reinforces the perovskite structure against the diverse stresses that plague these devices.

Moreover, beyond stability and efficiency, this innovation importantly facilitates improved charge transport mechanisms within the perovskite layer. The dual-site ion coordination influences the dynamics of hole transport, ensuring that charge carriers are separated and conveyed with greater efficiency throughout the device. Such improvements at the microscopic scale of ion and defect control culminate in macroscopic performance enhancements—essential for the realistic deployment of perovskite photovoltaics.

The success of this work illuminates a broader paradigm in photovoltaics: the necessity of molecular-level precision control for future device architectures. The composite nature of [12]-C-4POR exemplifies how multi-functional molecules can simultaneously tackle multiple degradation pathways, a concept that can be extrapolated to other hybrid materials and layered optoelectronic systems. The study underscores the indispensable role of interdisciplinary collaboration among chemists, physicists, and materials scientists in crafting innovative solutions to seemingly intractable challenges.

This research also shines a light on the crucial interplay between fundamental science and applied technology. Deciphering the complex interactions at the molecular interfaces enables rational design strategies, moving beyond serendipitous discoveries to targeted engineering approaches. In practice, this means that next-generation photovoltaic materials can be conceptualized with built-in resilience and optimized functionality rather than relying solely on trial-and-error methods.

The published work appearing in the journal Advanced Science represents a significant leap forward in the field of perovskite solar cells. It embodies an elegant fusion of chemistry and device engineering, where introducing a single hybrid compound simultaneously mitigates ion migration, passivates defects, enhances hole transport, and improves environmental stability. Such breakthroughs promise to expedite the integration of perovskite solar technology into commercial applications, spanning rooftop installations to large-scale solar farms.

Importantly, the leading scientists emphasize that this molecular umbrella concept symbolizes more than a technical achievement—it embodies the ethos needed for sustained innovation. Open-minded research collaborations, supported by funding entities such as the National Science Centre (grant SONATA BIS 10, no. 2020/38/E/ST5/00267), provide fertile ground for breakthroughs that transcend disciplinary boundaries. This spirit of cooperation is critical in tackling the complex molecular and materials challenges that define modern renewable energy research.

In summary, the development of the meso-crowned porphyrin-based [12]-C-4POR molecule represents a landmark advancement in perovskite photovoltaic technology. By addressing core degradation processes with a multifunctional molecular design, the researchers have paved the way for highly efficient, long-lasting solar cells that could dramatically alter the global renewable energy landscape. Continued exploration and refinement of such molecular architectures may soon unlock the full potential of perovskites, making solar energy more accessible, affordable, and sustainable for the future.

Subject of Research: Molecular engineering and stability enhancement of halide perovskite solar cells
Article Title: Dual-Functional Meso-Crowned Porphyrin Compound Enhances Efficiency and Stability in Perovskite Solar Cells
News Publication Date: Not specified
Web References: DOI 10.1002/advs.202522461
References: Advanced Science Journal, Institute of Physical Chemistry PAS publications
Image Credits: Grzegorz Krzyzewski, Przedsiębiorstwo Wodociągów i Kanalizacji Sp. z o.o. w Piasecznie