Eco-friendly light-emitting electrochemical cells developed using dendrimers

In a groundbreaking study published in the journal Advanced Functional Materials, researchers from Japan and Germany have made significant strides in the field of illumination by developing eco-friendly light-emitting electrochemical cells (LECs). This research could potentially usher in a new era of lighting technology.

Electroluminescence, the process of materials emitting light when an electric current passes through them, plays a crucial role in various modern applications, from the screens we use to lasers utilized in cutting-edge scientific research. Consequently, considerable resources are dedicated to enhancing this technology.

LECs, a promising emerging technology, have gained attention due to their cost advantage over organic light-emitting diodes (OLEDs) and their simplified structure. Unlike OLEDs that require intricate layering of multiple organic films, LECs can be manufactured with a single layer of organic film mixed with light-emitting materials and an electrolyte. The electrodes connecting these components can even be made from inexpensive materials, unlike the rare or heavy metals employed in OLEDs. Moreover, LECs operate at lower driving voltages, resulting in lower energy consumption.

The research teams led by Associate Professor Ken Albrecht from Kyushu University and Prof. Rubén D. Costa from the Technical University of Munich have been investigating new organic materials suitable for LECs. Their focus turned to dendrimers, branched symmetric polymeric molecules with a unique structure widely used in diverse fields such as medicine, sensors, and now optics.

The researchers modified their dendrimer materials for LEC applications, replacing hydrophobic molecular groups with hydrophilic ones. This modification significantly extended the device’s lifetime to over 1000 hours, more than tenfold from the original. Furthermore, the collaboration between the Japanese and German teams resulted in an environmentally friendly device.

Prof. Costa’s team in Germany had been dedicated to developing cost-effective and environmentally friendly materials for light-emitting devices. Among the materials explored was cellulose acetate, a commonly used organic compound found in various products, including clothing fibers and eyeglass frames. By employing cellulose acetate derived from biomass as the electrolyte in their LEC device, the team confirmed its long lifespan. Additionally, they discovered that graphene could serve as an electrode, a crucial advancement for creating flexible light-emitting devices using environmentally friendly materials.

While the research holds great promise, further investigation is required before these devices can be brought to market. The current device only illuminates in yellow, necessitating further development to emit the three primary colors of light: blue, green, and red. Improvements in luminescence efficiency are also necessary. Nevertheless, the collaboration between the international research teams points to a bright future for this field of study.

Source: Kyushu University

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