Method for the coaxial NW arrays, it is found that the incident light is effectively trapped in the coaxialNWsthrough absorption resonances so that the light absorption of the coaxial NWs can be significantly enhanced compared to that of c-Si NWs. Based on the Lorenz-Mie light scattering theory for the single coaxial NWs and the rigorous coupled-wave analysis Light absorption is investigated in coaxial nanowires (NWs) of crystalline silicon (c-Si) cores and amorphous silicon (a-Si) shells, including both cases of single coaxial NWs and coaxial NW arrays, for an incident light spectrum of 1.0–4.0eV covering the major solar band for photovoltaic cells. The possible reason of these findings is discussed. So, the use of SiNWs produced by the modified Au-MacEtch method as the antireflective material is favored over those prepared by Ag-MacEtch due to their higher light absorption and lower reflectance. Moreover, SiNWs prepared by Au-MacEtch demonstrate better antireflective properties in contrast to those formed by conventional Ag-assisted chemical etching. The total surface reflectance of 1~7% for SiNWs and ~17% for SiNPs was observed over the entire Si-absorbing region. The antireflective properties of these structures in comparison with NWs produced by the conventional Ag-MacEtch method were analysed. This modification allowed to obtain the close-packed Au nanodrop (ND) pattern that generates the nanowires (NWs) and the well-separated Au NDs, which induce the nanopore (NP) formation. For this purpose, we made different Au catalyst patterns on the surface of Si substrate. This work pertains to the method for modification of silicon (Si) wafer morphology by metal-assisted chemical etching (MacEtch) technique suitable for fabrication of antireflective Si surfaces. We can find that the ALD-Al 2 O 3 thin film (thickness ~40 nm) is homogeneous and conformal (see the inset c1), which benefits from the self-limiting gas–solid reaction between the precursors and substrate.
Solarcell texture series#
The average length of NWs is ~550 nm, and the diameter is in the range 70–80 nm.Figure 1(c) shows an oblique-view SEM figure of the Al 2 O 3 -coated (400 ALD cycles) surface of SiNWs for series A. Hence, we could denote a sample of a certain series by combing a capital letter with the number of ALD cycles, for example, D-250 means series D (SiNWs length ~1200 nm) with 250 ALD cycles (Al 2 O 3 thickness ~25 nm).Figure 1(b) illustrates the oblique-view SEM image of the Si N/M-Strus for series B consisting of the nanoscale SiNWs along crystal axis and microscale pyramid texture whose facets normal is along oriented direction, and the inset is the corresponding high magnitude cross-sectional imagine of SiNWs. Among each series, we used the number of ALD cycles, that is, 100, 250, 400, 500, and 700, to characterize the different Al 2 O 3 thickness on the Si N/M-Strus (note that one ALD cycle can form ~0.1-nm-thick Al 2 O 3 evaluated from the selflimiting reaction characteristics of ALD method).
A noticeable enhancement is found in all the characteristics of the novel structure with an estimated 32% increase in the total conversion efficiency over a cell without any light trapping mechanisms. The absorption profile, the external quantum efficient, and the power conversion efficiency of the suggested solar cell are calculated. The suggested multiscale simulation model integrates the finite-difference time-domain algorithm used in solving Maxwell's equation in three dimensions with a commercial simulation platform based on the finite element method for carrier transport modeling. The simulation was done using a new reliable, efficient and generic optoelectronic approach. A metal backreflector works additionally as the other contact. The upper electrical contact consists of an indium tin oxide layer, which serves also as an antireflection coating. In the proposed structure, the active layer is formed from an amorphous silicon thin film sandwiched between silicon nanowires from above and photonic crystal structures from below.
A novel structure for thin-film solar cells is simulated with the purpose of maximizing the absorption of light in the active layer and of reducing the parasitic absorption in other layers.
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