Incorporation of a self-aligned selective emitter to realize highly efficient (12.8%) Si nanowire solar cells

Abstract

Formation of a selective emitter in crystalline silicon solar cells improves photovoltaic conversion efficiency by decoupling emitter regions for light absorption (moderately doped) and metallization (degenerately doped). However, use of a selective emitter in silicon nanowire (Si NW) solar cells is technologically challenging because of difficulties in forming robust Ohmic contacts that interface directly with the top-ends of nanowires. Here we describe a self-aligned selective emitter successfully integrated into an antireflective Si NW solar cell. By one-step metal-assisted chemical etching, NW arrays formed only at light-absorbing areas between top-metal grids while selectively retaining Ohmic contact regions underneath the metal grids. We observed a remarkable ∼40% enhancement in blue responses of internal quantum efficiency, corresponding to a conversion efficiency of 12.8% in comparison to the 8.05% of a conventional NW solar cell.

Overcoming the Problem of Electrical Contact to Solar Cells Fabricated using Selective‐Area Silicon Nanopillars by Cesium Chloride Self‐Assembly Lithography as Antireflective Layer

“…[1][2][3][4][5][6][7] However, the experimental conversion efficiencies reported to date for such solar cells are much lower than the estimated theoretical efficiency. [8] One major hurdle is the difficulty in forming ar obusto hmic front electroded irectlyo ver the nanostructure arrays. Non-ohmic contacts formed between the top-electrodes and nanostructure arrays increaset he series resistance while decreasing the fill factor (FF).…”

Transparent conductor-embedding nanolens for Si solar cells

“…The previous researches suggest fundamental approaches for nanostructured solar cells. [1][2][3][4][5][6][7][8][9][10][11][12][13] Meanwhile, we can observe the limit in solar cell efficiencies. Additionally, a fancy concept has difficulty in the nanoscale fabrications and large-size applications.…”

“…Nanostructures have an enormous advantage to enlarge the surface area at a fixed volume, 10,12,13 which is a promising feature of nanoscale designs for solar cells. The enlarged surface spontaneously enhances the photon absorption in the light-active semiconductor layer.…”

Comment on “Facile Deposition of Ultrafine Silver Particles on Silicon Surface Not Submerged in Precursor Solutions for Applications in Antireflective Layer”

“…However, up to date, this state-of-the-art nanoscale zero reflector is not much effective to improve the practical solar cell performances. This is because of the overweighted design for optical aspects of nanoscale structured solar cells [5][6][7][8][9]. It also clearly suggests that there exists a discrepancy between the optical advantage and the electrical performances.…”