Newswise — Fukuoka, Japan—A groundbreaking study conducted by researchers from Japan and Germany has unveiled a significant advancement in the field of illumination, potentially heralding a new era in lighting technology. The team has successfully developed eco-friendly light-emitting electrochemical cells (LECs) using novel molecules known as dendrimers, combined with electrolytes derived from biomass and electrodes based on graphene. Their pioneering findings have been published in the esteemed journal Advanced Functional Materials.
Electroluminescence, the process by which materials emit light when subjected to an electric current, underpins numerous modern technologies, ranging from the displays on your device that enable you to read this text to state-of-the-art lasers employed in scientific research. Given its widespread application and indispensability in today's world, considerable resources are dedicated to research and development aimed at advancing this technology.
Associate Professor Ken Albrecht, a leading researcher from Kyushu University's Institute for Materials Chemistry and Engineering, elucidates an emerging technology known as "light-emitting electrochemical cells" (LECs). These cells have garnered considerable attention due to their cost advantages over organic light-emitting diodes (OLEDs) and their simplified structure.
Compared to OLED devices, which necessitate intricate layering of multiple organic films, making their manufacturing process intricate and expensive, LECs can be fabricated using a single layer of organic film mixed with light-emitting materials and an electrolyte. Furthermore, the electrode connecting these components can be crafted from inexpensive materials, in contrast to the rare or heavy metals utilized in OLEDs. Additionally, LECs operate at lower driving voltages, resulting in reduced energy consumption.
Prof. Rubén D. Costa, leading the research team at the Technical University of Munich in Germany, shares insights into their exploration of new organic materials suitable for implementation in LECs. One of the promising candidates they have focused on is dendrimers, which are branched symmetric polymeric molecules renowned for their diverse applications, spanning from medicine to sensors and now optics.
Building upon their previous advancements in dendrimer development, the research team embarked on modifying these materials specifically for LECs. Initially, the dendrimer they created possessed hydrophobic molecular groups that repelled water. However, through a significant breakthrough, they replaced these hydrophobic groups with hydrophilic counterparts, which exhibit an affinity for water. This crucial modification resulted in a remarkable extension of the LEC device's lifetime to over 1000 hours, surpassing the original duration by more than tenfold. Notably, the collaboration between Prof. Albrecht's team and Dr. Costa's team has ensured that the developed device remains highly eco-friendly.
Over the years, Dr. Costa's team in Germany has been dedicated to the pursuit of cost-effective and environmentally sustainable materials for light-emitting devices. Among the materials under experimentation is cellulose acetate, a commonly used organic compound found in various products, including clothing fibers and eyeglass frames.
Costa further elaborates, "In our newly developed LEC device, we employed cellulose acetate derived from biomass as the electrolyte, and we confirmed that it exhibits the same extended lifespan as our previous findings." He continues, "Additionally, we made a significant breakthrough by demonstrating that graphene can be utilized as an electrode. This crucial advancement brings us closer to realizing flexible light-emitting devices using environmentally friendly materials."
While the research team's achievements are indeed promising, they acknowledge that further research is required before these devices can be introduced to the market.
"The current device we have created only emits light in the yellow spectrum, so our next objective is to develop it to emit the three primary colors of light: blue, green, and red. We also need to enhance the luminescence efficiency, ensuring the brightness of the emitted light," Albrecht concludes. "Fortunately, thanks to our collaborative efforts on an international scale, the future holds great potential."
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