Abstract
Nano-resonators can be used in photovoltaics to drastically improve the ability of the device to absorb light and generate photo-carriers, therefore enabling a reduction of the absorber volume. Conventionally, the harvest of the spectrally broad solar spectrum is achieved via the tedious engineering of multiple optical resonances. In this paper, we propose a breakthrough approach, which consists in reducing the solar spectral range with a spectral conversion layer to match only one resonance that can then be easily designed. We use a Maxwell solver and a ray-tracing code to optimize the nano-resonator and its spectral converter. We show that 66.2% optical efficiency can be theoretically achieved in less than 40 nm mean thick absorber while leading to device design enabling collection of photo-generated carriers.
Highlights
One main axis of research in photovoltaics is the absorber volume reduction to drop costs and absorber material consumption, both issues of increasing importance as photovoltaic industry develops towards the TW scale
Due to technological progress in nano-fabrication during the last decades, in terms of control of features at subwavelength scales implemented on various materials, of devices based on light trapping in standard p/n diodes, as, e.g. based on InP with improvements above that of standard antireflection coatings [35] or in nanowires of various sorts were proposed by several research groups
Optical efficiency is the percentage of AM 1.5 photons below the bandgap that are absorbed by the photovoltaic cell
Summary
One main axis of research in photovoltaics is the absorber volume reduction to drop costs and absorber material consumption, both issues of increasing importance as photovoltaic industry develops towards the TW scale. Efforts have been focused to push absorber volume downwards to reach sub-wavelength dimensions [39,38], down to nanometer scale and 2D materials [37], while at the same time considering conditions for electrical collection of photo-generated carriers [40]. At this scale, finding a highly absorbing material is not enough to circumvent loss absorption, which leads to consider advanced light trapping strategies. If this point is considered, we note that in addition to reduce the absorber volume, ultra-thin absorber could improve charge collection by minimizing the photo-carrier recombination in the volume of the absorber
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