Boosting emission efficiency in light-emitting electrochemical cells with plasmonic nanoantennas

This project is financed by the Kempe foundations

Research question

Light extraction of thin film devices, such as light-emitting electrochemical cells, is an active research area because of their inherent low efficiency to outcouple light to the far field. Plasmonic excitations, collective oscillations of free electrons in metallic nano-objects driven by electromagnetic radiation, enable to control light scattering with extreme precision and can be used as a tool to improve light emission in devices such as light-emitting electrochemical cells. The main goal of this project is to show that it is possible to improve light-emitting electrochemical cells performance by recovering a large amount of the lost power by using plasmon-driven light scattering and waveguiding to the far field. In particular, we would like to answer the following research questions: can we use plasmonic antennas to direct at least 50% of the emitted light inside light-emitting electrochemical cells to the far field, thus improving the performance of the device and make it competitive on the market and enable the development of a stable and green light source? Furthermore, can we think about new types of optical antennas which do not need the use of metallic materials but instead use organic conductive polymers, thus making the new devices fully sustainable? Finally, it is worth mentioning the sustainability aspects of the project: light-emitting electrochemical cells are extremely easy to fabricate and do not need toxic and/or dangerous materials and are composed by fully recyclable materials. The strategy proposed in this project has the potential for the design of new devices based on light-emitting electrochemical cells technology, with a higher light outcoupling efficiency, thus opening excellent opportunities for a full commercialization of more sustainable and efficient light sources.

Sustainability aspects

Our project relates to the following Sustainability Development Goals (SDGs):

• Goal 1 – Affordable materials able to be produced and recycled, enabling economic advancement: LECs are a green light emitting technology which can be produced using low-cost and non-toxic materials. The components of such devices can be either recycled or disposed without harming the planet.
• Goal 4 – Affordable low-tech and high-tech materials for life-long learning and education: if we can prove that LECs can really become commercially competitive as light sources, we can replace this type of technology in the screen of our iPads, computers and eBooks, thus contributing to a more sustainable digitalization of learning and education environments.
• Goal 7 – Green materials for efficient technology and infrastructure to harvest, transport, store, and convert energy: as mentioned above, plasmonic LECs might be the game changer to produce green energy in form of light using sustainable materials for a more efficient light-emitting technologies.
• Goal 12 – Efficient (re)use/recycling of (natural) materials for sustainable production/consumption with lower chem release into soil, air and water: all the materials used in plasmonic LECs can be either recycled or disposed without harming the planet, as mentioned in the first point of this list.

Nevertheless, it is worth mentioning that at the moment there might be a conflict with ‘Goal 8 – Resource-efficient use of materials for processes enabling an increased value of (raw) materials’, as the fabrication technique we will exploit in our project requires the use of an EBL, thus of a clean room environment, as well as the purchase and the use of some materials which are not affordable (e.g., gold for our nanoantennas, which can eventually being replace by aluminum).

The sustainability significance of the project is reflected on the aforementioned link of the project goals/aims to the SDGs. The technology we would like to improve has a clear impact on both energy and materials efficiency, since these devices are a clean source of light/energy and the materials they are made of are more efficiently re-usable in the long run. Also, the materials used to fabricate plasmonic LECs have also the potential to reduce to the minimum the use of persistent or hazardous chemicals that can cause harm or accumulate in a circular flow. Moreover, many solvents used to fabricate LEC devices are also green, as proved by LE recently5. This means that this project will provide a positive impact also on more efficient and sustainable recycling processes, including the efficient (re-)use of the components of LECs devices. Our ambition is also to show that even plasmonic LECs can be low-cost and in the long run become devices which can be produced using cleanroom-free processes, thus allowing in the future to reduce output in terms of waste from production.