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Plasmonic Enhancement and Directionality of Emission for Advanced Luminescent Solar Devices

Periodic Reporting for period 4 - PEDAL (Plasmonic Enhancement and Directionality of Emission for Advanced Luminescent Solar Devices)

Berichtszeitraum: 2019-10-01 bis 2021-09-30

The current world consumption of energy is 17 TW per year. By mid-century (2050), the annual world energy consumption is projected to double. Harvesting solar energy has the potential to reduce carbon emissions and to provide clean energy to contribute to sustainable development. Most of the photovoltaic research to date has focused on achieving higher photovoltaic conversion efficiency at lower cost. In this research, a disruptive PV technology is described where record increases in efficiency have been achieved and costs reduced. Diffuse solar radiation has been captured to produce higher efficiencies with concentration ratios over 12 in Plasmonic Luminescent Solar Concentrators (PLSC) and Plasmonic Luminescent Downshifting thin-films (PLDS) have been tailored to increase the efficiency of all solar cells types independent of material composition. Finally, these novel systems were designed, up-scaled with the ability not only to generate higher power and increase solar device efficiencies but with the options for development of unique building integrated components.

PEDAL has developed a disruptive PV technology where record LSC concentration ratios have been achieved leading to costs of BIPV dramatically reducing;
(1) Diffuse solar radiation has been captured to produce higher efficiencies with concentration ratios over 12 in plasmonically enhanced luminescent solar concentrators (PLSC). This proposal has boosted efficiency utilising metal nanoparticles (MNP) tuned to luminescent material type in LSCs, to induce plasmonic enhancement of emission. MNP were investigated for alignment to enable directional emission within the LSC. These are both important steps in the reduction of loss mechanisms within the device and towards major increases in efficiency.
(2) Plasmonically enhanced luminescent downshifting thin-films (PLDS) have been tailored to increase efficiency of solar cells independent of material composition. Again MNP were used, where the plasmonic resonance was tailored to the luminescent species to downshift UV. MNP were investigated for alignment to enable directional emission within the PLDS layer, reducing losses enabling dramatic increases in a layer adaptable to all solar cells.
(3) These novel systems were designed, up-scaled and a building integrated component fabricated, with the ability not only to generate power but with options for demand-side management.
Previous work has been limited by quantum efficiency of luminescent species, with this breakthrough in both the use of MNP for plasmonic emission enhancement and alignment inducing directionality of emission, leading to efficiencies of both PLSC and PLDS being radically improved. PEDAL is a project based on new phenomena that has far-reaching technological impacts on solar energy conversion and light management technologies.
This project was based on developing Luminescent Solar devices both Luminescent solar concentrators (LSCs) and Luminescent downshifting layers (LDS) and then investigating the upscaling of these devices for building integration. The innovation in this project was the utilistaion of plasmonic coupling between MNPs and luminescent species to exploit the enhanced localized electric field generated by localized surface plasmon resonance (SPR) phenomena of MNPs. As it can strongly alter the optical properties of the luminescent species in terms of; absorption and fluorescence emission, excitation rate, fluorescence quantum yield, photo-stability, polarization state of fluorescence emission, directionality of fluorescence emission. Therefore, MNPs can play the role of an amplifier or damper for localized optical emitters (luminescent species) and allow the manipulation of optical properties. Plasmonic coupling can be controlled by; spacing between MNPs and luminescent species, orientation of MNPs with respect to luminescent species or vice-versa, refractive index of embedding medium, SPR wavelength of MNPs, and spectral overlap of SPR wavelength to the absorption and emission of the luminescent species.
This project developed
A process of MNP synthesis for LSCs and LDS for this application
A model (and software) to model plasmonic enhancement in both LSC and LDS
Small scale characterisation of both devices.
Directionality of emission was investigated and insights from this project provides huge scope and potential for further investigation
Largescale devices were fabricated and tested
A model developed to provide building integrated options to enable demand side management

Current exploitation is on developing a route to commercialisation of the software and manufacturing development on the fabrication processes for the devices.
During PEDAL, the intrinsic properties of the solar cells have not been modified. PLSC and PLDS use as photon conversion techniques and are optimized as an independent optical process, dissociated from the particular physical properties of the operating semiconductor material or solar cell architecture. As a result, the photon conversion devices may be combined with all existing solar cells devices. The optical option is much more versatile, allowing independent and unique research; a method of PV system improvement, lowering of thermalisation and easy implementation at industrial level.

This research is a completely new approach (based on plasmonics and directional emission in luminescent devices) for solar cell efficiency improvement, and has enabled long-term and high quality research which still has many questions to be answered . Not only is the underlying physical phenomena highly novel and unconventional, but PEDAL also avoids changing the composition of the PV materials, which would be the standard approach to this problem.

The final products of this project are new, completely portable, adaptable building component (PLSC) or as an efficient plastic matrices (PLDS) that will be suitable for their adaptation onto all types of solar panels.

PEDAL has been an ambitious project, with clear and specific goals both in the scientific and engineering aspects. The solutions derived by this project has meant and will mean not only a radical improvement of solar cell performance, but it is also ambitious research at the basic level with a view to industrial applications.

In summary, this project has enabled highly significant scientific advances in the field of photon energy conversion processes due to its originality, high scientific content and its expected results. Moreover, PEDAL is based on new phenomena that will allow very high technological impacts in terms of solar energy conversion. The progress beyond the state of the art are multiple: new knowledge, new advances for Science and new concrete results for plasmonic enhancement of emission in both PLSC and PLDS systems as well as the alignment of MNP enabling directional emission, as well as improved building integrated devices.
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