Optimisation numérique, par SCAPS-1D, des paramètres électriques d’une cellule solaire à base du silicium amorphe hydrogéné (a-Si:H)

Abstract

Numerical modelling is used to confirm experimental and theoretical work. The aim of this work is to present how to simulate an ultrathin hydrogenated amorphous silicon (a-Si:H) based solar cells with a BRL in their architectures and to reduce current leakage at the interfaces. These results are obtained by using SCAPS-1D software. First, the comparison between the J-V characteristics of the simulation and the experiment of the ultrathin solar cell a-Si:H-based shows that these curves are in agreement; proof of the validity of our solar cell model. On the other hand, to explore the impact of certain properties on the solar cell electrical parameters (JSC, VOC, FF and η), investigations show that the increase of the intrinsic layer thickness improves performance, while the bulk defects density of this layer and the surface defects density of the p-buffer layer/i-(a-Si:H) interface, respectively in the ranges [109 cm-3, 1015 cm-3] and [1010 cm-2, 5 × 1013 cm-2], do not affect the performance of the ultrathin a-Si:H-based solar cell. Analysis also shows that with approximately 1 μm thickness of the intrinsic layer, an efficiency of 12.71% is obtained (JSC = 18.95 mA.cm-2, VOC = 0.973 V, FF = 68.95 %). Secondly, J-V characteristics of solar cell with different BRLs (ITO, IGZO, ZnO, PCBM, TiO2, and CdS:O) were designed, simulated, and compared to numerically investigate the best back reflector layer (BRL) for a-Si:H-based ultrathin-film solar cells. Thus, the solar cell with ZnO BRL gives the best efficiency of 17.65% under STC, compared to other BRLs. The thickness being a parameter which limits the performance of a solar cell and the optimisation of the p-(a-SiOx:H) window layer thickness shows that with 5 nm, the a-Si:H-based solar cell efficiency is 18,00% (JSC = 18.93 mA/cm2,VOC = 1.077 V, FF = 88.32%). In addition, by varying the charge carrier lifetime of the absorber layer, we have optimized the thickness and carrier concentration of each layer of the device without and with n-type buffer layer introduced at the i-(a-Si:H)/n-(a-Si:H) interface to reduce current leakage at this interface. This improvement allowed us to obtain a maximum efficiency of 21.49% and a temperature coefficient of -0.184%/°C for the a-Si:H-based ultrathin-film solar cell with n-type buffer layer and aluminium (Al) as a back metal contact. This work presents a contribution to improving the performance of a-Si:H-based solar cells.