1,720,998 research outputs found
Polaron-exciton model for resonance energy transfer
No full textIt is shown that Förster's expression for the electronic energy transfer rate can be recast in a form predicted for exciton motion that interacts strongly with molecular vibrations. Using a simple model based on the Kennard-Stepanov theory, Förster's expression for the spectral overlap is shown to be of a thermally activated form, as obtained previously by multiphonon theory. In contrast, the high-frequency internal vibrations contribute a factor which results from tunneling through a potential barrier between potential curves in the configuration coordinate diagram. We thus show that resonance energy transfer is equivalent to phonon-assisted hopping of a trapped excitonic polaron
Ultra-thin silicon solar cell: modelling and characterisation
No full textAn ultra-thin crystalline silicon solar cell with an active silicon
layer of 200 nm has been fabricated and fully characterised
electrically (I-V characteristic, spectral response) and optically
(Variable Angle Spectroscopic Ellipsometry). Interference
effects were observed in the spectral response of the cell
due to multiple reflections from the layers within the cell. A
mathematical model was developed to account for the different
reflections and transmission within the cell which reproduced
excellently the essential features of the experimental
spectral response
Interference effects observed in ultra-thin c-si solar cells: modeling and experiment
No full textA crystalline silicon solar cell with an ultra-thin active silicon layer of 200 nm has been fabricated from SOI wafers. The cell was fully characterised electrically by measuring the I-V and spectral response measurements and optically by ellipsometry. The spectral response of the cell showed interference effects due to multiple reflections from the different layers within the cell structure. A mathematical model was developed based on multilayer film theory to account for the different reflections and transmissions with the cell structure. The theoretical spectral response predictions reproduced excellently the essential features of the measured spectral response
High aspect Ratio Sub-micron Pillars Fabricated by Photo Assisted Electrochemical Etching and Oxidation
No full textAn analysis of a "dead layer" in the emitter of n<sup>+</sup>pp<sup>+ </sup>solar cells
No full textIn this paper, the results obtained from fabrication and characterizations of n+pp+ solar cells are presented. The existence of a dead layer in the emitter was inferred regarding to the poor quantum efficiency of the cells under short wavelength region. The effects of this layer on the solar cell performance have been analyzed using the theoretical model and demonstrated in the term of low collection efficiency near the top surface of the emitter and high front surface recombination velocity
Characterisation of fluorescent collectors based on solid, liquid and Langmuir-Blodgett films
No full textHigh-Aspect ratio silicon pillars fabricated by electrochemical etching and oxidation of macroporous silicon
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