Researchers overcome obstacles to the functionalization of bio-inspired solar energy harvesting materials

Inspired by nature, researchers from the City College of New York (CCNY) can demonstrate a synthetic strategy for stabilizing bio-inspired solar energy harvesting materials. Their results, published in the latest issue o Chemical nature, could be a significant breakthrough in the functionalization of molecular assemblies for future solar energy conversion technologies.

In almost every corner of the world, despite the extreme conditions of heat or cold, you will find photosynthetic organisms trying to capture solar energy. Uncovering nature’s secrets on how to collect light so efficiently and robustly could transform the landscape of sustainable solar energy technologies, especially in the wake of rising global temperatures.

In photosynthesis, the first step (i.e. collecting light) involves the interaction between the light and the light-collecting antenna, which is made up of fragile materials known as supramolecular assemblies. From green leafy plants to tiny bacteria, nature has designed a two-component system: supra-molecular assemblies are embedded within protein or lipid scaffolds. It is not yet clear what the role of this scaffold is, but recent research suggests that nature may have evolved these sophisticated protein environments to stabilize their fragile supra-molecular assemblies.

“While we are unable to replicate the complexity of protein scaffolds found in photosynthetic organisms, we have been able to adapt the basic concept of a protective scaffold to stabilize our artificial light-collecting antenna,” said Dr. Kara. Ng. His co-authors include Dorthe M. Eisele and Ilona Kretzschmar, both professors at CCNY, and Seogjoo Jang, professor at Queens College.

So far, the translation of nature’s design principles into large-scale photovoltaic applications has not been successful.

“The failure may lie in the design paradigm of current solar cell architectures,” Eisele said. However, she and her research team “are not aiming to improve existing solar cell designs. But we want to learn from nature’s masterpieces to inspire entirely new solar energy harvesting architectures,” she added.

Inspired by nature, the researchers demonstrate how small cross-linking molecules can overcome the barriers to functionalization of supramolecular assemblies. They found that silane molecules can self-assemble to form a stabilizing, interlocking scaffold around an artificial supra-molecular antenna that collects light.

“We have shown that these inherently unstable materials can now survive in a device, even through multiple heating and cooling cycles,” said Ng. Their work provides proof of concept that a scaffold cage design stabilizes supramolecular groups against environmental stressors, such as extreme temperature fluctuations, without disrupting their favorable light-gathering properties.