In recent years, perovskite solar cells (PSCs) have emerged as one of the most promising candidates for next-generation photovoltaic technology, given their remarkable power conversion efficiencies and potentially low fabrication costs. However, one critical challenge that has impeded their widespread commercialization is their mechanical stability and durability, especially when integrated into flexible substrates for wearable or portable applications. In a groundbreaking study published in npj Flexible Electronics, Duan, Yang, Li, and colleagues have unveiled a novel approach to significantly enhance the mechanical robustness of flexible perovskite solar cells by employing selective self-assembled siloxane coupling agents in screen-printed architectures.
This advancement is particularly noteworthy because flexible PSCs often suffer from mechanical degradation under bending, stretching, or twisting stresses, which are inevitable in real-world applications. Traditional fabrication processes primarily focus on the photovoltaic performance in static conditions, neglecting the implications of mechanical fatigue over time. The research team’s innovative use of siloxane-based coupling agents leverages the unique chemical affinity between the perovskite active layers and underlying flexible substrates, creating a chemically bonded interface that mitigates delamination and crack propagation during mechanical strain.
At the heart of the method lies the selective self-assembly of siloxane molecules that act as molecular adhesives at critical interfaces within the solar cell stack. Unlike conventional adhesives or binders, these siloxanes spontaneously form ordered monolayers through covalent bonding and hydrogen bonding interactions, resulting in a conformal and highly stable interfacial layer. This carefully engineered interface not only enhances the adhesion between the perovskite layer and the flexible substrate but also preserves the intrinsic optoelectronic properties essential for high-efficiency energy conversion.
Importantly, the researchers employed screen printing as their deposition technique for creating the perovskite layers and associated transport layers. Screen printing is well-known for its scalability, cost-effectiveness, and compatibility with flexible substrates, but it has historically presented challenges related to film uniformity and mechanical integrity. The integration of siloxane coupling agents into this process provides a dual advantage: it enables the retention of desirable photovoltaic performance metrics while vastly improving the mechanical endurance of the resulting devices under repeated deformation.
Mechanistic studies conducted by the team revealed that the siloxane coupling agents form robust Si–O–Si and Si–O–metal bonds at the interface, facilitating stress distribution during mechanical cycling. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses demonstrated markedly reduced crack formation and propagation in siloxane-treated devices compared to control samples. Furthermore, the devices exhibited a minimal drop in power conversion efficiency (PCE) after thousands of bending cycles, underscoring the practical durability imparted by this interface engineering strategy.
The significance of these findings extends beyond mere mechanical stability; they point toward the possibility of integrating flexible perovskite solar cells into wearable electronics, Internet of Things (IoT) devices, and other emerging applications demanding both high efficiency and mechanical resilience. The adaptability of the self-assembled siloxane layer to various flexible substrates, including polymers like polyethylene terephthalate (PET) and polyimide, makes this approach broadly applicable across the flexible electronics landscape.
Moreover, the researchers highlighted that the selective nature of the siloxane assembly process enables precise control over interfacial chemistry without compromising the perovskite crystal growth or morphology. This aspect is critical because the electronic properties of perovskite materials are highly sensitive to surface interactions and defects. By preserving the delicate balance between chemical bonding and electronic passivation, the siloxane-treated devices maintain outstanding photovoltaic parameters such as open-circuit voltage, short-circuit current density, and fill factor.
Advances in flexible PSCs like this study address a crucial bottleneck hindering the integration of perovskite photovoltaics into versatile form factors. While traditional rigid silicon solar cells dominate the market, their inflexibility and fragility limit usage in wearable and foldable technologies. The ability to screen print mechanically robust perovskite cells opens the door to low-cost manufacturing of solar panels that could be embedded in clothing, backpacks, or even curved building surfaces, transforming the way solar energy is harvested.
Beyond just mechanical durability, the chemical strategy employed offers potential protection against environmental factors such as moisture and oxygen ingress, common causes of perovskite degradation. Siloxane monolayers are known for their hydrophobic and chemically inert properties, which could synergistically enhance the overall stability of flexible PSCs when combined with encapsulation techniques. This layered defense mechanism could extend operational lifetimes to commercially viable durations.
The convergence of scalable screen printing and molecular interface engineering represents an important paradigm shift. Instead of relying solely on bulk material improvements or encapsulation, tuning the interfacial chemistry introduces a new dimension of device reliability that can be adapted post-fabrication. The method demonstrated by Duan et al. thus contributes significantly to the roadmap for flexible solar cell commercialization.
Looking ahead, the conceptual framework could be extended to other thin-film photovoltaic technologies, including organic solar cells and quantum dot-enhanced devices. The modularity of siloxane chemistry implies that tailoring the molecular composition could optimize interfaces for different active layer materials, opening avenues for hybrid and tandem device architectures. Furthermore, integration with roll-to-roll manufacturing systems could enable mass-market production of wearable solar fabrics.
The research not only provides a technical blueprint for overcoming the mechanical fragility of flexible PSCs but also showcases the importance of interdisciplinary approaches combining chemistry, materials science, and device engineering. The study’s insights into molecular self-assembly and interfacial bonding underline how subtle control at the nanoscale dictates macroscopic device performance.
In conclusion, the innovative use of selective self-assembled siloxane coupling agents in screen-printed flexible perovskite solar cells marks a significant milestone toward durable, efficient, and scalable photovoltaic technologies tailored for the flexible electronics era. This breakthrough paves the way for next-generation wearable and portable solar energy solutions that can withstand the rigors of daily use without sacrificing performance, potentially transforming energy harvesting in a sustainable and user-friendly manner.
Subject of Research: Flexible perovskite solar cells, mechanical stability, interface engineering, siloxane coupling agents, screen printing technology.
Article Title: Mechanically stable screen-printed flexible perovskite solar cells via selective self-assembled siloxane coupling agents.
Article References:
Duan, M., Yang, J., Li, T. et al. Mechanically stable screen-printed flexible perovskite solar cells via selective self-assembled siloxane coupling agents.
npj Flex Electron 9, 30 (2025). https://doi.org/10.1038/s41528-025-00407-6
Image Credits: AI Generated
