No abstract

No abstract

a b s t r a c tLuminescent solar concentrators are low cost photovoltaic devices, which reduce the amount of necessary semiconductor material per unit area of a solar collector by means of concentration. The device is comprised a thin plastic plate in which luminescent species (fluorophores) have been incorporated. The fluorophores absorb the solar light and radiatively re-emit part of the energy. Total internal reflection traps most of the emitted light inside the plate and wave-guides it to a narrow side facet with a solar cell attached, where conversion into electricity occurs. The efficiency of such devices is as yet rather low, due to several loss mechanisms, of which self-absorption is of high importance. This work demonstrates that type-II semiconductor hetero-nanocrystals may offer a solution to the self-absorption problem in luminescent solar concentrators.

No abstract

This article is made publicly available in the institutional repository of Wageningen University and Research, under the terms of article 25fa of the Dutch Copyright Act, also known as the Amendment Taverne. This has been done with explicit consent by the author.Article 25fa states that the author of a short scientific work funded either wholly or partially by Dutch public funds is entitled to make that work publicly available for no consideration following a reasonable period of time after the work was first published, provided that clear reference is made to the source of the first publication of the work.This publication is distributed under The Association of Universities in the Netherlands (VSNU) 'Article 25fa implementation' project. In this project research outputs of researchers employed by Dutch Universities that comply with the legal requirements of Article 25fa of the Dutch Copyright Act are distributed online and free of cost or other barriers in institutional repositories. Research outputs are distributed six months after their first online publication in the original published version and with proper attribution to the source of the original publication.You are permitted to download and use the publication for personal purposes. All rights remain with the author(s) and / or copyright owner(s) of this work. Any use of the publication or parts of it other than authorised under article 25fa of the Dutch Copyright act is prohibited. Wageningen University & Research and the author(s) of this publication shall not be held responsible or liable for any damages resulting from your (re)use of this publication.

No abstract

The measurement of mass resolved ion energy distributions at the grounded substrate in an RF glow discharge allows to determine the ion flux and the ion energy flux towards the surface of a growing hydrogenated amorphous silicon (a-Si:H) layer. This provides the means to study the influence of ions on the structural properties of a-Si:H. Here we focus on the α-γ’ transition as occurs in silane-hydrogen plasmas at an RF frequency of 50 MHz and a substrate temperature of 250 °C. The structural properties of the layers appear to depend on the kinetic energy of the arriving ions. This is supported by measurements of ion fluxes under other deposition conditions and by characterization of the corresponding layers. The influence of ions on the growth is discussed in terms of their flux, and the amount of delivered kinetic and potential energy to the growing film. The measurements suggest that a threshold energy of about 5 eV per deposited atom is needed for the construction of a dense amorphous silicon network.

For the first time ion energy distributions (IED) of different ions from silane-hydrogen (SiH4-H2 ) RF plasmas are presented, i.e. the distributions of SiH3+, SiH2+ and SiH2+. The energy distributions of SiH3+ and SiH3+ ions show peaks, which are caused by a charge exchange process in the sheath. A method is presented by which the net charge density in the sheath is determined from the plasma potential and the energy positions of the charge exchange peaks. Knowing the net charge density in the sheath and the plasma potential, the sheath thickness can be determined and an estimation of the absolute ion fluxes can be made. The flux of ions can, at maximum, account for 10% of the observed deposition rate.