International Journal of Latest Technology in Engineering, Management & Applied Science (IJLTEMAS) Volume VI, Issue IV, April 2017 | ISSN 2278-2540
Impact of Defects and Ambient Temperature on the Performance of HIT Solar Cell Ambar Khanda1, Malay Saha2 and Tapas Chakrabarti3 ECE Department, Heritage Institute of Technology, Kolkata, India Abstract: Heterojunction with intrinsic thin layer or “HIT” solar cells are considered favorable for large-scale manufacturing of solar modules, as they combine the high efficiency of crystalline silicon c-Si solar cells, with the low cost of amorphous silicon technology. This article is based on the ambient temperature and the defects density in the Hetero-junction with Intrinsic Thin layers solar cells (HIT) strongly influences their performances. In this paper the structure: ITO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/aSi:H(n)/ITO is presented where we study the effect of the ambient temperature and the defects density in the gap of the crystalline Silicon layer and amorphous Silicon intrinsic layer on the performance of the heterojunction solar cell with intrinsic layer (HIT). The structure is simulated in AFORS-HET simulation software environment. Keywords: Defect, Temperature, HIT, AFORS-HET
Hahn-Meitner Institute of Berlin and is used for Simulating the hetero-junction solar cells [6],[7]. The software provides a convenient way to evaluate the role of the various parameters (thickness, doping concentration, band gap etc.) present in the fabrication process of HIT solar cells. II. STRUCTURE OF THE HIT SOLAR CELL The HIT solar cell structure is ITO/a-Si:H(p)/a-Si:H(i)/cSi(n)/a-Si:H(n)/ITO and the structure is shown in Fig1. In this HIT solar cell structure, a-Si(p), a-Si(i), c-Si(n), a-Si(n) layers are used as emitter, buffer, absorber and BSF layers respectively[5,8]. A study of the performance evolution, basedon the defects density parameters and ambient temperature is performed for this structure.
I. INTRODUCTION
ITO(contact)
n today's fast growing world, solar energy has become one of the most focused sources of obtaining „green‟ energy in last few decades.
a-Si:H(p)(10nm)
I
The hetero-junction solar cells (HJ) are obtained by joining two materials with different energy gaps (Eg). Hetero-junction was first studied in 1974 by Fuhs [1] and in 1983 the first heterojunction solar cell was fabricated [2-3]. Heterojunction with intrinsic thin layer or “HIT” solar cells is combined of the high stable efficiency of crystalline silicon (c-Si) cells with the low temperature deposition technology of hydrogenated amorphous silicon (a-Si:H).The resulting cells can achieve high conversion efficiencies, while using the thin film silicon reduces the cost of the HIT cell compared to the c-Si solar cells [4]. In the year 1994, the first HIT solar cell was developed by „SANYO‟ Ltd [5]. In November 2014, the Panasonic Corporation (Sanyo) announced a record efficiency of 25.6% at research level using HIT solar cell.
a-Si:H(i)(7nm) c-Si(n)(300um)
a-Si(n)(10nm) ITO(contact)
Fig1: Schematic Structure of the HIT solar cell
In this paper the structure: ITO/a-Si:H(p)/a-Si:H(i)/c-Si(n)/aSi:H(n)/ITO is presented and a study on the effects of the ambient temperature and the defects densities in the gap of the crystalline Silicon layer on the performance of the HIT solar cell is performed in AFORS-HET simulation software environment.
In this structure the thickness of the a-Si(p), a-Si(i), c-Si(n) and a-Si(n) layers are taken as 10nm, 7nm, 300um and 10 nm respectively.
AFORS-HET (Automat FOR Simulation of Heterostructures) software has been developed by a group from the
Table1: Parameter values of different layers[9] [10] [11] [12]
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Many other standard parameters are taken into consideration in the present simulation and their values are reported in table 1.
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