Researchers at the Indian Institute of Science Education and Research (IISER) Kolkata have developed an innovative method that utilizes organic nanotubes to harness artificial light, offering a wide range of applications in solar cells, photocatalysis, optical sensors, and tunable multi-color light-emitting materials.

The concept behind this advancement lies in the intricate energy transfer process observed in plants and photosynthetic bacteria.

In recent years, researchers have sought to replicate and understand these natural systems to develop highly efficient energy conversion and storage technologies.

Supratim Banerjee, in collaboration with Suman Chakrabarty from the S. N. Bose National Center for Basic Sciences (SNBNCBS), embarked on experimental and computational investigations focused on artificial light-harvesting using organic nanotubes.

The Methodology

The nanotubes were created through the union of an organic fluorescent molecule and a therapeutically important biopolymer.

The fluorescent molecule, known as cyano stilbenes, exhibits enhanced emission in its aggregated state, while the biopolymer, called heparin, is an anionic substance with crucial therapeutic applications.

In the presence of heparin, the cationic cyano stilbenes self-assembled into nanotubes that emitted a vibrant greenish-yellow light.

This electrostatically driven co-assembly process allowed the nanotubes to act as highly efficient energy donors, akin to the antenna chromophores found in photosynthetic bacteria.

They could donate energy to acceptor dyes like Nile Red and Nile Blue, enabling the tuning of emission colors from greenish yellow to orange-red, even producing white light.

This energy transfer phenomenon, known as Förster resonance energy transfer (FRET), has far-reaching implications in various domains, including DNA/RNA structure determination, biological membrane mapping, and real-time PCR tests.

As the world increasingly focuses on converting solar energy into chemical or electrical forms for storage, efficient energy transfer processes play a pivotal role in such applications.

The researchers’ study, published in Chemical Science, the journal of the Royal Society of Chemistry, delved into the formation of these nanotubes using absorption and fluorescence spectroscopy, transmission electron microscopy (TEM), and fluorescence lifetime imaging microscopy (FLIM).

With the advancement in light-harvesting technology, the potential for more efficient solar cells, enhanced photocatalysis, advanced optical sensors, and customizable multi-color light-emitting materials becomes increasingly tangible.

In March 2023, a  group of researchers at the University of Cambridge successfully manipulated the initial steps of photosynthesis and uncovered a novel approach to harnessing its energy.

In January 2023, researchers at the École Polytechnique fédérale de Lausanne (EPFL) invented a solar-powered device that is capable of harvesting water from the air for conversion into hydrogen fuel.