Large‐Area Boron‐Doped 1.6 Ω cm p‐Type Czochralski Silicon Heterojunction Solar Cells with a Stable Open‐Circuit Voltage of 736 mV and Efficiency of 22.0%

Stefani, Bruno Vicari; Soeriyadi, Anastasia; Wright, Matthew; Chen, Daniel; Kim, Moonyong; Zhang, Yuchao; Hallam, Brett

doi:10.1002/solr.202000134

Cited by 13 publications

(9 citation statements)

References 27 publications

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“…In p‐type SHJ solar cells, surface‐related recombination affecting the low‐injection range is known to severely limit the FF of such devices. [ 74,92,107 ] This was illustrated by Descoeudres et al in 2013, where SHJ solar cells fabricated with n‐ and p‐type FZ‐Si wafers with conversion efficiencies >21% were compared. [ 107 ] In their report, despite both p‐ and n‐type devices achieving comparable peak‐ V OC values the conversion efficiency of the champion p‐type SHJ solar cell (21.38%) was limited by a ≈1.3% abs lower FF when compared to the champion n‐type device (22.14%).…”

Section: Surface Passivation Of P‐type C‐si Wafersmentioning

confidence: 99%

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Silicon Heterojunction Solar Cells and p‐type Crystalline Silicon Wafers: A Historical Perspective

et al. 2022

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The first reports of both boron–oxygen (BO)‐related light‐induced degradation (BO‐LID) and amorphous/crystalline silicon heterojunction (SHJ) solar cell fabrication date back to the early 1970s. However, the complete development of the “modern” SHJ structure took place well before BO defect stabilization processes were developed. Due to the susceptibility of p‐type Czochralski (Cz)‐grown silicon to BO‐LID, such wafers were deemed unsuitable for SHJ solar cells. In addition to stability issues, lower charge carrier lifetimes due to contamination and challenges with surface passivation posed barriers to the adoption of p‐type wafers in SHJ applications. Herein, these three key challenges are discussed in detail. Kinetic modeling and experimental results reveal the severe impact of BO‐LID in p‐type SHJ solar cells and provide possible explanations as to why earlier attempts using p‐type wafers might have failed. The role of gettering and advanced hydrogenation in stabilizing BO defects in SHJ solar cells is demonstrated experimentally. Finally, a summary of the effective surface recombination velocities reported in the literature for hydrogenated intrinsic amorphous silicon passivation of p‐ and n‐type crystalline silicon wafers is presented. Based on these findings, the potential of p‐type wafers to enable a next‐generation of high‐efficiency solar cells featuring carrier‐selective contacts is discussed.

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Section: Surface Passivation Of P‐type C‐si Wafersmentioning

confidence: 99%

“…It was shown that the continuous improvements in wafer lifetime, stability, and surface passivation quality of p‐type c‐Si have enabled stable V OC values compatible with the SHJ technology. [ 48,62,74 ]…”

Section: Final Thoughtsmentioning

confidence: 99%

Silicon Heterojunction Solar Cells and p‐type Crystalline Silicon Wafers: A Historical Perspective

et al. 2022

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“…Figure displays the result of the same BO LID light‐soaking test. The V OC in the control, which is markedly lower than the defect‐engineered results displayed by Vicari Stefani, [ 86 ] displays a similar degradation profile. However, the control cell that undergoes the post‐cell AHP treatment is stable.…”

Section: Defect Engineering Approachesmentioning

confidence: 71%

“…Vicari Stefani et al investigated the impact of BO LID in p‐type SHJ cells. [ 86 ] Commercial‐grade p‐type Cz wafers, with resistivity of 1.6 Ω cm, were used to ensure that the boron concentration was similar to that used for industrial PERC solar cells. These wafers were fabricated into full‐area (244.32 cm 2 ) p‐type SHJ cells in an industrial environment at Meyer Burger, Germany.…”

Section: Defect Engineering Approachesmentioning

confidence: 99%

Progress with Defect Engineering in Silicon Heterojunction Solar Cells

Wright

Stefani

Soeriyadi

et al. 2021

Physica Rapid Research Ltrs

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Silicon heterojunction (SHJ) solar cells are formed by the deposition of stacks of intrinsic and doped hydrogenated amorphous silicon layers (a-Si:H) on the surface of crystalline silicon (c-Si) wafers. [1][2][3] The doped a-Si:H layers determine the carrier selectivity of each contact, which defines the direction of current flow, and the intrinsic a-Si:H layers, which are deposited directly onto the crystalline silicon (c-Si) surface, provide excellent surface passivation. [4,5] The cells are completed by the deposition of a transparent conducting oxide (TCO) to aid lateral conduction and the formation of metal contacts, typically by screen printing of silver. [6][7][8] This technology was pioneered in the 1990s by Japanese company Sanyo. [9][10][11] The solar photovoltaics (PV) market is currently dominated by the passivated emitter and rear cell (PERC) design. [12,13] Compared to PERC, SHJ solar cells have multiple advantages. They have demonstrated higher open circuit voltages (V OC ), with V OC values as high as 750 mV. [9] The high V OC is related to the excellent surface passivation provided by the a-Si:H layers. The world record 1 sun efficiency of 26.7% for a single-junction silicon solar cell was achieved using this approach, [14] and cells with efficiency exceeding 25% have been fabricated in an industrial environment. [15] Another advantage of SHJ cells, which is linked to the high V OC , is the lower temperature coefficient, meaning that power losses in SHJ cells operated at elevated temperatures are lower than in other siliconbased technologies. [2,16] Therefore, under realistic cell-operation conditions in the field, the actual power output of an SHJ module will be higher than that of a PERC module, even if they have the same power rating at room temperature. In addition, the expected rise of tandem solar cells with silicon as the bottom cell has also increased interest in the SHJ technology, as it is well suited as the bottom cell in a tandem device. [17][18][19][20][21][22] These advantages mean that industry is seriously looking into SHJ solar cells as a technology to compete with PERC in the future. The ITRPV 11th edition indicates that the market share for SHJ cells is expected to increase to 15% over the next ten years [23] which will represent a significant volume as we move toward terawatt-scale photovoltaics. [24] One unique aspect of SHJ cells is that all processing occurs in a low-temperature regime, typically <250 C. [4,16,25] This is very different to most other cell architectures, such as aluminium

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“…In PERC cells, the addition of such a process can have the dual impact of increasing the efficiency and improving the stability. 2,22,23 Although extensive work over the past 10 years has led to the development of hydrogenation processes in p-type technologies, 24,25 far less studies have explored the potential benefits of incorporating hydrogenation processes into the production of high-efficiency n-type passivated contact solar cells. 26 In this report, the impact of a post-cell hydrogenation process on the performance of n-type TOPCon solar cells fabricated at JinkoSolar is explored.…”

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confidence: 99%

24.58% efficient commercial n‐type silicon solar cells with hydrogenation

Chen

Wright

Chen

et al. 2021

Progress in Photovoltaics

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Tunnelling oxide passivated contact (TOPCon) solar cells are gaining significant commercial interest, due to the potential for high efficiency. Industrially, this passivated contact scheme is typically coupled with an n-type Czochralski (Cz) wafer. JinkoSolar Holding Co., Ltd. is one of the leading manufacturers that are producing n-type TOPCon solar cells (referred to as 'HOT' cells) on a commercial scale. In this work, the influence of a post-cell hydrogenation step, using illumination from an LED light source, on the performance and stability of n-type TOPCon solar cells is investigated.The incorporation of this additional hydrogenation treatment led to an average efficiency enhancement of 0.64% abs on a batch of 50 cells made in an industrial environment. This significant improvement was caused by a 6.9 mV and 1.04% abs increase in open-circuit voltage (V OC ) and fill factor (FF), respectively. We also assessed the stability and found almost no light-and elevated temperature-induced degradation (LeTID) in hydrogenated n-type TOPCon cells. Testing at 70 ± 5 C under 1-sun illumination revealed that the maximum degradation is limited to 0.06% rel .Following further stability testing, the efficiency increased beyond the initial value, up to 0.4% rel increase after 120 h. By incorporating this hydrogenation process into the production, an average line efficiency of 24.08% and V OC of 707.5 mV was achieved. The champion cell from the batch displayed an efficiency of 24.58%, as certified by measurement at the Chinese Academy of Sciences.

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Large‐Area Boron‐Doped 1.6 Ω cm p‐Type Czochralski Silicon Heterojunction Solar Cells with a Stable Open‐Circuit Voltage of 736 mV and Efficiency of 22.0%

Cited by 13 publications

References 27 publications

Silicon Heterojunction Solar Cells and p‐type Crystalline Silicon Wafers: A Historical Perspective

Silicon Heterojunction Solar Cells and p‐type Crystalline Silicon Wafers: A Historical Perspective

Progress with Defect Engineering in Silicon Heterojunction Solar Cells

24.58% efficient commercial n‐type silicon solar cells with hydrogenation

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