| Sep 18, 2025 |
Perovskite solar cells heal themselves with dendrimersDendrimers enable perovskite solar cells to recover from moisture damage by capturing key components, allowing repeatable self-healing without sacrificing efficiency. |
| (Nanowerk Spotlight) Solar panels that can heal themselves might sound like science fiction, but the idea is rooted in a practical problem that has slowed one of the most promising technologies in clean energy. Perovskite solar cells are lightweight, flexible, and highly efficient. They have emerged as a serious alternative to traditional silicon panels. |
| These cells can be printed at low temperatures, tailored for different applications, and made from readily available materials. In laboratory conditions, their ability to convert sunlight into electricity now matches or exceeds that of silicon. But one weakness continues to limit their use outside the lab. They are chemically fragile and lose performance rapidly when exposed to moisture. |
| The active materials in these devices, called lead halide perovskites, begin to fall apart in the presence of water. Even short exposure can trigger chemical reactions that strip away key ingredients, destabilize the structure, and reduce the device’s ability to function. The result is a steep decline in performance and, often, permanent damage. |
| Engineers have tried to manage this with barrier layers that block water, or by modifying the chemistry to make the material more robust. These methods offer some improvement, but they cannot stop the underlying damage from occurring. Without a way to restore the material itself, these devices remain vulnerable. |
| A more direct solution is to give the material the ability to repair itself. If a perovskite film could recover from damage on its own, it might survive repeated exposure to stress without permanent loss of function. But this kind of self-healing requires precise control. |
| Some previous studies have used large organic molecules that help trap the fragments lost during degradation. These can slow the damage, but they also tend to interfere with the electrical properties of the film. Adding bulk or blocking charge movement can lower efficiency or cause unwanted side effects. The challenge is to provide chemical support without undermining performance. |
| A new study published in Advanced Materials ("Sustainable Self‐Healing of Perovskite Solar Cells Using Dendrimers as Volatile Reservoirs") offers a more finely tuned solution. Researchers in South Korea have developed a special class of branched molecules called dendrimers that can act as both stabilizers and temporary storage sites for the key components lost during breakdown. |
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| Repeatable self-healing properties of perovskite solar cells (PSCs) with multifunctional dendrimer. a) Molecular structure of the fourth-generation bis-MPA-NHBoc dendrimer (NHD) and schematic illustrating the NHD-FAPbI3 perovskite solar cell (NHD-PSC). b) J–V characteristics of NHD-PSC measured after degradation and recovery. c) Recovery cycling tests of pristine PSC and NHD-PSC based on normalized PCE. d) Planar-view SEM images and photographs of pristine FAPbI3 and NHD-FAPbI3 films in different states: initial, degraded, and recovered. (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge) |
| Dendrimers are precisely engineered, tree-like molecules with a compact core and multiple layers of repeating branches. This structure allows them to carry many chemical groups in a small volume and interact with their surroundings in controlled ways. In this case, they are designed to hold and then release the building blocks needed for repair. Their size and symmetry make them well suited to fit within the perovskite material without disrupting its structure. Unlike earlier additives, they do not interfere with the material’s electrical properties. |
| In solar cells made with these dendrimers, the perovskite layer can repeatedly recover after moisture exposure while maintaining high efficiency. This approach introduces a new way to make solar cells more resilient by embedding recovery mechanisms directly into the material itself. |
| The study presents a material-level intervention that enables solar cells to recover from environmental damage without external repair. The team designed a dendrimer called NHD with two kinds of functional groups. The interior contains carboxylate groups that can form hydrogen bonds with formamidinium molecules. These molecules are easily lost during degradation but are essential for maintaining the crystal structure. The dendrimer’s outer branches contain amine groups that coordinate with lead ions in the perovskite, helping to stabilize the structure and reduce ion movement that leads to defects. |
| These dendrimers were mixed into the solution used to create the perovskite layer, specifically one based on formamidinium lead iodide. The resulting films showed several improvements over untreated samples. The crystal grains were larger and more uniform. There were fewer grain boundaries, which are typically weak points where moisture tends to infiltrate and chemical breakdown begins. |
| X-ray diffraction revealed improved orientation and crystal quality. Surface measurements confirmed that the dendrimers helped suppress the formation of charge trapping sites, and current flow through the material was more uniform. |
| When solar cells made from these dendrimer enhanced films were tested under alternating cycles of humid and dry conditions, they performed noticeably better than standard devices. After ten such cycles, the dendrimer based devices retained over 90 percent of their original power conversion efficiency. Untreated devices lost performance quickly and did not recover. Photoluminescence measurements showed that the dendrimer based films returned almost completely to their original optical state after each recovery period. The self healing behavior was repeatable and sustained. |
| Chemical analysis revealed how the dendrimers supported this recovery. When the perovskite degraded, components such as formamidinium and iodide tended to evaporate or form byproducts. In untreated films, lead oxide and other irreversible products began to form. In dendrimer treated films, these reactions were suppressed. Nuclear magnetic resonance showed that lead atoms maintained a local environment similar to that of the intact perovskite, even after degradation. |
| X-ray photoelectron spectroscopy confirmed that iodide loss was reduced and the lead iodide framework remained intact. The dendrimer’s functional groups appeared to hold the escaping molecules in place, allowing them to be reabsorbed during the recovery phase. |
| Molecular simulations supported these findings. The researchers modeled how formamidinium, water, and hydrogen iodide interacted with the dendrimer. Water was weakly bound and diffused rapidly, allowing it to leave the film after damage. Formamidinium was more strongly bound and less mobile. It remained on the dendrimer surface and was available for reintegration into the crystal. These binding patterns helped explain how the material could reassemble itself after water exposure. Hydrogen bonding and coordination with lead helped maintain the overall structure during degradation. |
| An important aspect of the process was the formation of intermediate phases. Instead of breaking down completely, the degraded perovskite entered less stable but still partially ordered phases. These included what are known as 4H and 6H polytypes, which retain elements of the original structure. The dendrimers appeared to stabilize these phases, holding the lattice together just enough to allow it to return to its original form when conditions improved. Once the water had evaporated, the dendrimers helped guide the crystal back to its optimal cubic structure. |
| This method shares some similarities with light induced self healing, a process observed in some perovskite materials where light exposure can help reverse minor damage. The dendrimer approach differs in that it does not require external light or energy input. It works through direct chemical interactions and can operate in ambient conditions. This opens up the possibility of self-healing in indoor or low light environments where light based mechanisms would be less effective. |
| While the synthesis of dendrimers is more complex than adding a standard additive, the chemistry involved is well understood. The molecules can be produced with high purity and consistent structure. The researchers report good reproducibility across multiple devices and suggest that the approach could be adapted for scalable manufacturing. Because the dendrimers are integrated into the material rather than applied as a coating, they offer a route toward intrinsic stability that does not depend on external protection. |
| The work shows that it is possible to design additives that actively participate in the repair of a perovskite material without compromising performance. By combining structural stabilization with selective chemical binding, the dendrimer allows the perovskite to degrade in a controlled and reversible way. This avoids the permanent damage that limits many current devices. It also provides a template for how similar molecular strategies could be applied to other sensitive materials used in electronics, displays, or energy storage. |
| By embedding a chemical mechanism for recovery directly into the solar cell material, this study demonstrates a path toward longer lasting, more reliable perovskite technologies. The ability to recover from stress without intervention could help shift perovskites from a laboratory success story into a viable platform for real world energy applications. |
By
Michael
Berger
– Michael is author of four books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology (2009),
Nanotechnology: The Future is Tiny (2016),
Nanoengineering: The Skills and Tools Making Technology Invisible (2019), and
Waste not! How Nanotechnologies Can Increase Efficiencies Throughout Society (2025)
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