Passivation of Interfaces in High-Efficiency Photovoltaic Devices

Abstract

Solar cells made from III-V materials have achieved efficiencies greater than 30%. Effectively ideal passivation plays an important role in achieving these high efficiencies. Standard modeling techniques are applied to Ga 0.5 In 0.5 P solar cells to show the effects of passivation. Accurate knowledge of the absorption coefficient is essential (see appendix). Although ultralow (<2 cm/s) interface recombination velocities have been reported, in practice, it is difficult to achieve such low recombination velocities in solar cells because the doping levels are high and because of accidental incorporation of impurities and dopant diffusion. Examples are given of how dopant diffusion can both help and hinder interface passivation, and of how incorporation of oxygen or hydrogen can cause problems.

Design of a GaInP/GaAs tandem solar cell for maximum daily, monthly, and yearly energy output

“…It is assumed that the band structure in the range of interest (1.82 and 1.98 eV) is similar enough to the ≈1.89 eV case so that an assumed set of absorption coefficients, α (λ) (based upon a concatenation of coefficients published by Schmiedel et al 31 and Kurtz et al 16 ), at this bandgap can be shifted up and down in energy to obtain the absorption coefficients throughout the range of interest.…”

“…Nevertheless, the ideal-diode-based model is not as useful of a tool for design because it cannot provide the optimal sub-cell base layer thicknesses. A more complicated formulation of the simple model 14,15 may be used for this purpose, but again, even these formulations make several simplifying assumptions about carrier recombination and material quality 16 that are not assumed in the detailed model.…”

“…A comparison of the results achieved using these detailed models to those found using a simpler model shows that while the simple model shows similar trends, it cannot correctly predict the optimal design parameters unless a more complicated formulation, such as Hovel's equations, 14,15 are employed. However, these models also make several simplifying assumptions about carrier recombination and material quality 16 that are not assumed in a detailed numerical model.…”

Moth eye antireflection coated GaInP/GaAs/GaInNAs solar cell

“…Based on the geometry, we estimate that the surface area of the moth eye structure is approximately three times larger than that for the TiO 2 /SiO 2 reference structure [3]. However, based on PC1D simulations with different AlInP window thicknesses, we did not see remarkable differences even when a recombination velocity as high as 10 7 cm/s was considered instead of more typical 10 4 cm/s to 10 5 cm/s rates [15]. We believe that the most of the losses are caused by the absorption losses of AlInP [3].…”

Lasing of whispering‐gallery modes in GaInP waveguide micro‐discs and rings with InP quantum dots

“…The spectra were excited by 488 nm from an Ar ion laser. The effective pumping power was estimated from the disk thickness d=0.15 μm, reflectivity at the disk surface R≈30%, absorption coefficient inside the disk α≈46,700 cm -1 which is calculated from Kurtz's model [8], and the multiple absorption in the disk expressed as…”