Nanoimprinted backside reflectors for a-Si:H thin-film solar cells: critical role of absorber front textures.

The development of optimal backside reflectors (BSRs) is crucial for future low cost and high efficiency silicon (Si) thin-film solar cells. In this work, nanostructured polymer substrates with aluminum coatings intended as BSRs were produced by positive and negative nanoimprint lithography (NIL) techniques, and hydrogenated amorphous silicon (a-Si:H) was deposited hereon as absorbing layers. The relationship between optical properties and geometry of front textures was studied by combining experimental reflectance spectra and theoretical simulations.

Optimization of imprintable nanostructured a-Si solar cells: FDTD study.

We present a finite-difference time-domain (FDTD) study of an amorphous silicon (a-Si) thin film solar cell, with nano scale patterns on the substrate surface. The patterns, based on the geometry of anisotropically etched silicon gratings, are optimized with respect to the period and anti-reflection (AR) coating thickness for maximal absorption in the range of the solar spectrum. The structure is shown to increase the cell efficiency by 10.

Quantized electron states in nearly depleted hexagonal nanowires.

The hexagonal quantum well (QW) is studied as a model for hexagonal nanowires, and the effects of donor impurities and geometrical deformations of the well are treated. By use of the Poisson equation the donor potential is calculated and the eigenspectrum of the hexagonal QW is shown to converge to that of a paraboloid quantum well with increasing donor density. Small deformations of the hexagon are shown to change the eigenspectrum significantly and give strong splittings of degenerate eigenvalues.