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Communication Dans Un Congrès Année : 2014

ZnO nanoparticles as down-shifting material

Résumé

Most of the existing solar conversion plants are equipped with Si based PV cells. This technology will most certainly prevail for the coming decades. Therefore, any strategy that can help to increase the conversion efficiency, even slightly, is welcome; and all the more if it is cost-effective. One such possibility is to use a material that could convert the high energy radiation from the sun spectrum, namely UV and blue light, which are otherwise inefficiently absorbed by the Si based PV cells, and re-emit them at lower energy for which the conversion efficiency of the Si cell is optimum. The so-called “down-shifting” strategy belongs to the “add-on” technology. In technology, the aim is to fabricate a thin layer of the down-shifting material that could be added on top of existing cells at low cost. The criteria to fulfill are to design a material with as large a Stoke shift (discrepancy between absorption and emission energies) as possible with high luminescence external quantum efficiency (EQE). Furthermore, the material has to be environmental-friendly and cheap. Several attempts have been made to design such a material. CdS and CdSe nanoparticles embedded in polymers or silica have proved to be efficient but not necessarily cheap and environmental-friendly. Si nanoparticles in silica have been an alternative to chalcogenides. At the INL (institute of nanotechnology of Lyon), we develop down-shifting materials based on ZnO nanoparticles. ZnO is a low cost abundant and non-toxic material. It naturally absorbs the blue and UV radiations thanks to a band gap of about 3.37 eV at room temperature. ZnO can also emit visible light, from yellow to red, depending on the nature of the crystalline defects involved in the process. Even though the nature of these defects is still partially debated, it is established that reducing the size down to the nanoscale enhances their presence and efficiency. Therefore, we base our strategy on ZnO nanoparticles dispersed and embedded in a polymer matrix. In the present work, we will examine the efficiency of ZnO nanoparticles as down-shifting material. We will address the prominent issue of optimizing the EQE, in conjunction with the nano and mesotruscture. We will show how the chemical synthesis process affects the EQE and how we can use it to reach EQE larger than 20%. The possibility to disperse and embed the particles and polymers (PMMA for instance) will be discussed.
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Dates et versions

hal-01490298 , version 1 (15-03-2017)

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  • HAL Id : hal-01490298 , version 1

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Bruno Masenelli, Aleksandra Apostoluk, Yao Zhu, T. Cosnier, P. Gautier, et al.. ZnO nanoparticles as down-shifting material. 2014 Korea Institute of Science and Technology - the Institute of Multidisciplinary Convergence of Matter (KIST-IMCM) Symposium, May 2014, Seoul, South Korea. ⟨hal-01490298⟩
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