Current Photovoltaic Research

Korea Photovoltaic Society (한국태양광발전학회)
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Improved Understanding of LeTID of Single-crystalline Silicon Solar Cell with PERC

  • Received : 2018.10.16
  • Accepted : 2018.12.19
  • Published : 2018.12.31
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Abstract

Light elevated temperature induced degradation (LeTID) was noted as an issue in multi-crystalline silicon solar cells (MSSC) by Ram speck in 2012. In contrast to light induced degradation (LID), which has been researched in silicon solar cells for a long time, research about both LeTID and the mechanism of LeTID has been limited. In addition, research about LeTID in single-crystalline silicon solar cells (SSSC) is even more limited. In order to improve understanding of LeTID in SSSC with a passivated emitter rear contact (PERC) structure, we fabricated four group samples with boron and oxygen factors and evaluated the solar cell characteristics, such as the cell efficiency, $V_{oc}$, $I_{sc}$, fill factor (FF), LID, and LeTID. The trends of LID of the four group samples were similar to the trend of LeTID as a function of boron and oxygen.

Keywords

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Fig. 1. Schematic diagram of (a) conventional A-BSF cell structure and (b) PERC

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Fig. 2. Four ingot qualities including (a) Oi, (b) Resistivity, (c) Cs, and (d) MCLT (Red numbers show the difference value compared to the value of Group-4 as reference)

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Fig. 3. Texturing images of all groups

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Fig. 4. MCLT pattern images before and after heat treatment (Red numbers show the difference between value of average MCLTand value of Group-4 as reference)

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Fig. 5. Cell performance values including (a) Voc, (b) Isc, (c) FF, and (d) cell efficiency before LID (Red numbers show the difference value from value of Group-4 as reference)

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Fig. 6. The (a) LID and (b) cell efficiency after LID (Red numbers show the difference value from value of Group-4 as reference, and LID [%] is percent calculation based on efficiency)

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Fig. 7. Relative Voc degradation at elevated temperature of 130℃ with Isc-injection for current equivalent to 1 sun illumination

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Fig. 8. The (a) LeTID and (b) cell efficiency after LeTID (Red numbers show the difference value from the value of Group-4 as reference)

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Fig. 9. Comparison of LID and LeTID (Blue and red numbers show difference values of LID and LeTID compared to values of Group-4 as reference)

Table 1. Four group conditions

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Table 2. Reflectiveness of all groups

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