وبسایت مهندسی الکترونیک و کامپیوتر

An effective and optimised BSF layer is an important layer in both single junction and multijunction solar cells. In this work the use of the double layer BSF for top cell with their varied thicknesses is investigated on GaInP/GaAs DJ solar cell using the computational numerical modelling TCAD tool Silvaco ATLAS. The detail photo-generation rates are determined. The major modelling stages are described and the simulation results are validated with published experimental data in order to describe the accuracy of our results produced. For this optimized cell structure, the maximum Jsc ¼ 17.33 mA/cm2, Voc ¼ 2.66 V, and fill factor (FF) ¼ 88.67% are obtained under AM1.5G illumination, exhibiting a maximum conversion efficiency of 34.52% (1 sun) and 39.15% (1000 suns).

The presence and performance of the tunnel junction layer and back surface field (BSF) layers is the chief reason behind the high efficiency of the multi-junction solar cells. In this work, the focus is on thes election of a suitable material for the tunnel junction along with introducing a new top BSF layer. The simulation work is carried out in ATLAS TCAD. The various performance parameters like open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF) and efficiency (n) are extracted from the proposed solar cell model and are compared with published results to ascertain the accuracy of the present work. Other parameters like the photogeneration rate, spectral response, potential developed,electric field are also determined. I–V curve and the power curve are also plotted for the proposed model.For this proposed structure VOC= 2.668 V, JSC= 18.2 mA/cm2, FF = 88.29% and EFF = 40.879% are obtained for 1000 suns illuminated under standard AM1.5G spectrum. The obtained outputs and the modeling steps are elaborately explained.
 

An optimized BSF (Back Surface Field) is a key layer for a multi junction or single junction solar cell. In this work, two BSF layers with different thicknesses have been used in the upper and the lower cell and simulations have been done using the Silvaco ATLAS numerical modelling tools. It has been also found that in under the current matching condition with thinner upper BSF layers (160 nm, 30 nm) and a thicker lower BSF layer (1000 nm, 30 nm), JSC short circuit current density and VOC open circuit voltage and conversion efficiency solar cell is improved. Major steps of simulation and its description and results have been compared to the previously published data in order to describe accuracy of the results. By selecting the best thickness of BSF layer, the efficiency can be increased up to 15% which happens because of increase in photo-generation rates and absorption in the solar cells. This article shows some characteristics of the proposed dual junction solar cell such as photo-generation rate, short circuit current density, open circuit voltage and efficiency of the device relative to thickness of BSF layers and change in materials of tunnel junction. The results show that in case of increase in thickness of BSF, efficiency is also increased. The highest efficiency is obtained in thickness of 160 nm, then the efficiency is decreased. The values of Jsc = 23.36 mA/cm2, Voc = 2.43 V, FF = 86.76% and η = 47.78% (1 sun) have also been obtained under AM1.5G illumination in the proposed structure which shows improvement in performance of the proposed device.
 

Abstract - Reducing the recombination rate and increasing the photo-generation rate play a very significant role in improving the performance of the solar cells. In this research, AlGaAs has been used instead of GaAs in emitter layer with reduction in thicknesses of the base in order to decrease the recombination rate and increase the efficiency of the proposed solar cell. In addition, tunnel junction, buffer junction and BSF layers have been optimized to achieve higher efficiency. The efficiency can be improved by selecting optimal thickness of the materials because of the increase in photo-generation rate and absorption rate, improving transparency of the tunnel area and reducing the recombination rates of the solar cells. The results showed that after optimization, JSC (short circuit current density), VOC (open circuit voltage) and the η (conversion efficiency) of the solar cell are clearly increased. Also, the results of simulation were compared to the other designs in order to compare its performance. In the proposed structure, values of Voc= 2.52 V, Jsc= 29.09 mA/cm2, FF=86.49% and η= 62.04% (1 sun) are obtained under AM1.5G illumination.  

تاکنون مطالب زیادی در خصوص مدلسازی عملکرد افزاره‌ها و شبیه‌سازی رفتارشان منتشر شده‌اند که تقریباً تمام ابعاد مدلسازی، از سطوح میکروسکوپی الکتریکی تا سطوح میکروسکوپی مولکولی، را پوشش می‌دهند. البته اغلب مطالب این کتب آموزشی به صورت کلی گفته شده و مطالب ریز مربوط به نحوه شبیه‌سازی در آن نادیده گرفته شده‌اند. بنابراین نیاز است که مدل‌ها به‌صورت دقیق‌تر بررسی شده تا درک بهتری از موضوع حاصل شود. نکته دیگری که در بعضی از آموزش‌ها مشاهده می‌شود این است که در آنها اشکالات برنامه نویسی دیده می‌شود و مشکلات مهم مربوط به نحوه نوشتن کدها در سیلواکو ناگفته مانده‌اند. این امر موجب شده تا روند یادگیری این برنامه با کندی مواجه شده و گهگاه خواننده کتاب از ادامه کار منصرف شود. به‌علاوه هر یک از خطاهای شبیه‌سازی می‌تواند محقق را مشغول پارامترهای جزیی زیادی کند که سردرگمی فراوانی را به‌دنبال خواهد داشت. تمام موارد فوق موجب می‌شوند تا شبیه‌سازی کامل یک افزاره، کاری بسیار طاقت فرسا باشد.