Nasim Sahraei

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Light management in the Si bottom cell of a GaAs/Si tandem system is crucial due to the bandgap mismatch of the two materials, which results in a low current of the bottom cell. To evaluate the light coupling and light trapping, we developed an optical model to simulate the light absorption in the silicon bottom cell. This optical model is an extension of(More)
Light scattering superstrates are important for thin-film a-Si:H solar cells. In this work, aluminum-induced texture (AIT) glass, covered with nonetched Al-doped ZnO (AZO), is investigated as an alternative to the commonly used planar glass with texture-etched AZO superstrate. Four different AIT glasses with different surface roughnesses and different(More)
Light scattering at randomly textured interfaces is essential to improve the absorption of thin-film silicon solar cells. Aluminium-induced texture (AIT) glass provides suitable scattering for amorphous silicon (a-Si:H) solar cells. The scattering properties of textured surfaces are usually characterised by two properties: the angularly resolved intensity(More)
Flat-panel tandem solar cells have demonstrated the potential to exceed the efficiencies of their single-junction constituents. However, robust design rules for tandem solar cells are currently lacking, slowing the development of cost-effective implementations of this technology. A double-junction solar cell with four-terminal (4T) architecture stacks two(More)
We numerically evaluate the device impact of photon re-absorption on InGaP/Si tandem solar cells using a coupled optical-electronic device model. The presented simulation results provide guidelines for designing high performance InGaP/Si tandem device. We find that including the effects of photon recycling (PR) and luminescent coupling (LC) results in a(More)
Light trapping is of very high importance for silicon photovoltaics (PV) and especially for thin-film silicon solar cells. In this paper we investigate and compare theoretically the light trapping properties of periodic and stochastic structures having similar geometrical features. The theoretical investigations are based on the actual surface geometry of a(More)
In this paper, we present a loss analysis for an in-house fabricated 4-terminal GaAs/Si tandem solar cell with a conversion efficiency of 21.3%. Current losses are broken down into ten loss channels and quantified. In order to predict the current gains from individual improvements, we set each parameter associated with one of the loss channels to its ideal(More)
In this study, we propose a geometric optical model to represent alkaline saw-damage-etched (SDE) surfaces of monocrystalline silicon wafers. An experimental study is carried out to characterize the optical properties of alkaline SDE surfaces on monocrystalline silicon wafers. Based on the surface characteristics measured by goniometry and height profiling,(More)
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