Two-dimensional computer modeling of single junction a-Si:H solar cells (original) (raw)
Related papers
2014
We offer a numerical simulation tool, AMPS-1D, which allows to model homo- as well as heterojunction devices. AMPS-1D is the short form of automat for simulation of heterostructures. The program solves the one dimensional semiconductor equations in steady-state. Furthermore, a variety of common characterization techniques have been implemented, current-voltage, external quantum efficiency, conduction and valence band. A user-friendly interface allows to easily perform parameter variations, and to visualize and compare your simulations. In this work, The silicon heterojunction cell performances are investigated by detailed described on external quantum efficiency, and light current-voltage characteristics by recognized simulator AMPS-1D (Analysis of Micro-electronics and Photonic Structures). The objective of this work is to study the correlation between the emitter properties of both heterojunction cells a-Si:H/c-Si and a-SiC:H/c-Si (absorption, defect profiles and energy band offse...
Solar Energy Materials and Solar Cells, 2010
In this paper, single and multi-junction solar cells based on hydrogenated amorphous silicon (a-Si:H) and its alloy amorphous silicon carbide (a-SiC:H) are analyzed using one dimensional simulator AMPS-1D (Analysis of Microelectronic and Photonic Structures). Effects of thickness and doping concentration of different layers as well as the operating temperature on cell efficiency have been investigated with a view to find a more efficient and stable cell. For the single junction cell, the maximum efficiency of 19.62% has been achieved for a thickness of 500 nm of i-layer, which further improved to 20.8% after the optimization of the doping concentration. In case of double junction cell, the highest efficiency of 20.19% was found for top i-layer thickness of 700 nm after optimizing the bottom cell parameters. For the triple junction cell, parameters of the bottom cell and middle cell were optimized and the maximum efficiency of 21.89% was found with the top i-layer thickness of 600 nm. As regards the operating temperature, the double junction and the triple junction tandem cells showed better stability, with temperature gradient of 0.17% and 0.18%/C, respectively, than the single junction cell of 0.23%/C. The overall investigation on amorphous silicon solar cells as done here gives potential parametric suggestion that may lead to the fabrication of the high efficiency and stabilized a-Si thin film solar cells.
Numerical modeling of an amorphous-silicon-based p-i-n solar cell
IEEE Transactions on Electron Devices, 1990
A recently developed simulation program for amorphoussilicon-based p-in solar cells allows for accurate calculation of singleor multijunction cell response under monochromatic or global AM1.5 illumination. The device model is based on a complete set of Poisson and current continuity equations describing the amorphous intrinsic and microcrystalline or amorphous n+ and p+ contacts. It predicts solar cell behavior with uniform and nonuniform optical (mobility) bandgaps, spatially dependent doping densities, and various intrinsic layer thicknesses as demonstrated by the very good agreement between the experimental and simulated current-voltage characteristics of single cells, with the bandgaps in the range of 1.75 to 1.47 eV. The material parameters used in the simulation have been obtained from experimental results reported in the literature. We have also been investigating the possibility of obtaining higher efficiencies using novel cell designs. Calculations have been carried out on cell structures in which the bandgap of the intrinsic layer is profiled to help hole transport (through the increased internal electric field arising from valence band affinity grading). The most efficient structure, also confirmed by recent experimental data, incorporates normal profiling throughout the bulk of the intrinsic layer with a thin graded buffer at the p+-intrinsic junction. * imaging applications.
Analysis of high efficiency amorphous silicon single and multijunction solar cells
2009 1st International Conference on the Developements in Renewable Energy Technology (ICDRET), 2009
Amorphous silicon (a-Si) is widely used as material for photovoltaic because of its properties. In this work, the models of amorphous Si based solar cells are single junction with a-SiC:H/a-Si:H/ a-Si:H structure, double junction with a-SiC:H/ a-Si:H/ a-Si:H/¿c-SiC:H/ ¿c-SiC:H/ ¿c-SiC:H and multi junction a-SiC:H/a-Si:H/ a-Si:H /a-SiC:H/ a-Si:H/ a-Si:H/ a-SiC:H/ ¿c-SiC:H /a-Si:H. This structure will be designed and analyzed by using
Thin Solid Films, 2004
We have developed a Kramers-Kronig consistent analytical expression to fit the measured optical functions of hydrogenated amorphous silicon (a-Si:H) based alloys, i.e., the real and imaginary parts of the dielectric function (⑀ 1 ,⑀ 2 ) ͑or the index of refraction n and absorption coefficient ␣͒ versus photon energy E for the alloys. The alloys of interest include amorphous silicon-germanium (a-Si 1Ϫx Ge x :H) and silicon-carbon (a-Si 1Ϫx C x :H), with band gaps ranging continuously from ϳ1.30 to 1.95 eV. The analytical expression incorporates the minimum number of physically meaningful, E independent parameters required to fit (⑀ 1 ,⑀ 2 ) versus E. The fit is performed simultaneously throughout the following three regions: ͑i͒ the below-band gap ͑or Urbach tail͒ region where ␣ increases exponentially with E, ͑ii͒ the near-band gap region where transitions are assumed to occur between parabolic bands with constant dipole matrix element, and ͑iii͒ the above-band gap region where (⑀ 1 ,⑀ 2 ) can be simulated assuming a single Lorentz oscillator. The expression developed here provides an improved description of ⑀ 2 ͑or ␣͒ in the below-band gap and near-band gap regions compared with previous approaches. Although the expression is more complicated analytically, it has numerous applications in the analysis and simulation of thin film a-Si:H based p-i-n and n-i-p multilayer photovoltaic devices. First, we describe an approach whereby, from a single accessible measure of the optical band gap, the optical functions can be generated over the full solar spectrum for a sample set consisting of the highest quality intrinsic a-Si:H based alloys prepared by plasma-enhanced chemical vapor deposition using the principle of maximal H 2 dilution. Second, we describe quantitatively how such an approach can be modified for sample sets consisting of lower quality alloy materials. Finally, we demonstrate how the generated optical functions can be used in simulations of the absorption, reflection, and quantum efficiency spectra of a-Si:H based single-junction and multijunction solar cells.
International Journal of Photoenergy, 2012
The conversion efficiency of a solar cell can substantially be increased by improved material properties and associated designs. At first, this study has adopted AMPS-1D (analysis of microelectronic and photonic structures) simulation technique to design and optimize the cell parameters prior to fabrication, where the optimum design parameters can be validated. Solar cells of single junction based on hydrogenated amorphous silicon (a-Si:H) have been analyzed by using AMPS-1D simulator. The investigation has been made based on important model parameters such as thickness, doping concentrations, bandgap, and operating temperature and so forth. The efficiency of single junction a-Si:H can be achieved as high as over 19% after parametric optimization in the simulation, which might seem unrealistic with presently available technologies. Therefore, the numerically designed and optimized a-SiC:H/a-SiC:H-buffer/a-Si:H/a-Si:H solar cells have been fabricated by using PECVD (plasma-enhanced chemical vapor deposition), where the best initial conversion efficiency of 10.02% has been achieved (V oc = 0.88 V, J sc = 15.57 mA/cm 2 and FF = 0.73) for a small area cell (0.086 cm 2). The quantum efficiency (QE) characteristic shows the cell's better spectral response in the wavelength range of 400 nm-650 nm, which proves it to be a potential candidate as the middle cell in a-Si-based multijunction structures.
A computer analysis of double junction solar cells with a-Si:H absorber layers
Solar Energy Materials and Solar Cells, 1998
An integrated electrical-optical model has been used to examine the design of double junction solar cells, where the component cells have a-Si : H absorber layers of identical material quality in the initial state. The model takes into account both specular interference effects; and diffused reflectances and transmittances due to interface roughness. The carrier transport at the junction between the two p-i-n subcells is simulated with the help of a thin heavily defective "recombination" layer with a reduced mobility gap.
Key issues for accurate simulation of a-Si:H / c-Si heterojunction solar cells
Energy Procedia, 2011
Accurate simulation of a-Si:H / c-Si heterojunction (HET) solar cells is mandatory for acquiring a deeper understanding of device physics, better knowledge of material properties, and thus improving solar cells efficiency towards the 26% theoretical limit. The purpose of this paper is to provide relevant guidelines and to highlight key issues for accurate and physicallybased HET solar cells simulation. The need for a 2D simulation approach is demonstrated, together with an accurate description of the device optical performance. For the first time, a unified set of models and material parameters is proposed for reproducing experimental IV characteristics under illumination and obscurity conditions, considering state-of-the-art material parameters and localized defects. Finally, the key role of solar cell simulation is demonstrated for further device optimization.