BioLED uses luminescent proteins to produce white light
The device renders the same effect as produced by traditional inorganic LEDs but at a lower cost.
LEDs are manufactured using inorganic materials that are in short supply – such as cerium and yttrium – that makes them more expensive and less sustainable in the longer term. Additionally, white LEDs produce a colour that is not optimal for eyesight since they lack a red component that can psychologically affect individuals exposed to them for long periods of time.
The German-Spanish team of scientists has drawn inspiration from nature’s biomolecules in search of a solution. Their technique consists in introducing luminescent proteins into a polymer matrix to produce luminescent rubber. The technique involves a new way of packaging proteins which could end up substituting the technique used to create LEDs today. Details are published in the journal ‘Advanced Materials’.
"We have developed a technology and a hybrid device called BioLED that uses luminescent proteins to convert the blue light emitted by a ‘normal’ LED into pure white light," explained Rubén D. Costa to Sinc, a researcher at the University of Erlangen-Nürnberg (Germany) and co-author of the study.
It is always necessary to have either a blue or an ultraviolet LED to excite the rubbers that are put over the LED in order to make it white. In other words, the scientists can combine blue LED/green rubber/red rubber, or ultraviolet LED/blue rubber/green rubber/red rubber. The result claims to be the first BioLED that gives off a pure white light created by similar parts of the colours blue, green and red, all while maintaining the efficiency offered by inorganic LEDs.
The authors claim that the blue or ultraviolet LEDs are much cheaper than white ones, which are made of an expensive and scarce material known as YAG:Ce (Cerium-doped Yttrium Aluminium Garnet). The idea is replace YAG:Ce by proteins.
"The Bio-LEDs are simple to manufacture and their materials are low-cost and biodegradable, meaning that they can easily be recycled and replaced," poined out Costa, while also highlighting the high stability of these proteins that have "luminescent properties that remain intact during the months of storage under different environmental conditions of light, temperature and humidity".
"We have been able to achieve a sustained use of proteins in optoelectronic devices with an excellent stability for the first time, something that had not happened in the last 50 years. This thus represents a major breakthrough in this field," explained Pedro B. Coto, another one of the authors who also conducts research at the German university.
Scientists are already working on optimizing the new elastic material in order to achieve greater thermal stability and an even longer operating lifetime. They are addressing how to optimize the chemical composition of the polymer matrix in addition to using proteins that are increasingly more resistant to device operating conditions.
Michael D. Weber ,Lukas Niklaus, Marlene Pröschel, Pedro B. Coto, Uwe Sonnewald, Rubén D. Costa. "Bioinspired Hybrid White Light-Emitting Diodes". Advanced Materials 27(37): 5493-8, 2015. Doi: 10.1002/adma.201502349
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