Modelling, simulation, optimization of Si/ZnO and Si/ZnMgO heterojunction solar cells
| Autor: | S. Vallisree, Trupti Ranjan Lenka, R. Thangavel |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Polymers and Plastics Silicon chemistry.chemical_element 02 engineering and technology engineering.material 01 natural sciences Band offset law.invention Biomaterials law 0103 physical sciences Solar cell Common emitter 010302 applied physics business.industry Open-circuit voltage Doping Metals and Alloys Heterojunction 021001 nanoscience & nanotechnology Surfaces Coatings and Films Electronic Optical and Magnetic Materials Polycrystalline silicon chemistry engineering Optoelectronics 0210 nano-technology business |
| Zdroj: | Materials Research Express. 6:025910 |
| ISSN: | 2053-1591 |
| DOI: | 10.1088/2053-1591/aaf023 |
| Popis: | Currently, crystalline and polycrystalline silicon wafer based solar cells dominate the photovoltaic market, which employs expensive manufacturing processes. Zinc oxide is one among the inexpensive alternatives for acting as emitter/anti-reflection coating layer which can be used in combination with widely available p-type silicon. Hence it becomes essential to gain in-depth knowledge about the charge transport mechanisms involved in the n-type ZnO/p-type silicon (Si) heterojunction devices. Therefore, Si/ZnO solar cell is modeled and the carrier transport mechanisms are carefully examined by analyzing the band edge discontinuities, electric field distributions at the Si/ZnO interface, carrier generation-recombination profile for varying ZnO thickness, carrier density and affinity values. The photo- generation rate degrades with the increase in ZnO emitter thickness owing to increased absorption in the blue region and is independent of ZnO affinity and donor concentration. The cliff like configuration with high conduction band discontinuity at the Si/ZnO interface for higher values of ZnO affinity has resulted in the formation of poor electric field and the lattice mismatch resulting in high defects formation (recombination centers) at Si/ZnO interface are the predominant causes for deficit in open circuit voltage and fill factor. Hence the conduction band offset alignment is further engineered by designing Si/MgZnO solar cell model and Mg doped ZnO emitter has significantly improved the band offset alignment at the p-n heterojunction when compared to ZnO emitter. Moreover, the simulation results revealed that the stronger electric field strength developed at the heterojunction is suggested to favor the carrier separation process by drift motion thereby improving the open circuit voltage and fill factor of the device. As a next step, both the models are optimized for varying emitter parameters like thickness, carrier density etc using Silvaco ATLAS simulator. Based on this investigation, the optimized Si/ZnO and Si/MgZnO designs anticipate improved conversion efficiencies of 11.57% and 14.46% respectively. |
| Databáze: | OpenAIRE |
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