Carrier Lifetime Degradation and Regeneration in Gallium- and Boron-Doped Monocrystalline Silicon Materials

Winter, Michael; Walter, Dominic; Schmidt, Jan

doi:10.1109/jphotov.2021.3070474

Cited by 21 publications

(15 citation statements)

References 21 publications

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“…Although the defect concentration still increases by a factor of ~ 5 between degradation at 80 °C and 140 °C, the extent of degradation shown in Fig. 5 is lower than what we measured in our previous study 20 . The overall defect concentration in our present study is lower by a factor of 10.…”

Section: Resultscontrasting

confidence: 72%

“…The (temporary) recovery takes about 15–30 min at 0.5 suns and ~ 44 °C. Details can be found in our recent publication 20 .…”

Section: Resultsmentioning

confidence: 99%

“…However, there are also more recent studies reporting lifetime instabilities on Ga-doped Cz-Si wafer materials 18 – 21 , and most recently performance degradation of Ga-doped PERC modules 17 . Our own investigations showed that the temperature, at which the light-induced degradation is performed, has a strong impact on the extent of bulk lifetime degradation in Ga-doped Cz-Si 20 . With increasing temperature the extent of degradation is also increasing.…”

Section: Introductionmentioning

confidence: 92%

“…With increasing temperature the extent of degradation is also increasing. In our recent study 20 , we demonstrated e.g. that illumination of 1 Ω cm Ga-doped Cz-Si wafers performed at 140 °C may result in carrier lifetimes in the fully degraded state τ d of around ~ 500 µs (initial lifetime τ 0 was ~ 2300 µs).…”

Section: Introductionmentioning

confidence: 95%

“…The reported lifetimes were measured at an excess carrier concentration of Δ n = 10 15 cm −3 . Another interesting observation was that the illumination intensity used for defect activation can have an impact on the degradation extent 19 , 20 .…”

Section: Introductionmentioning

confidence: 99%

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Light and elevated temperature induced degradation and recovery of gallium-doped Czochralski-silicon solar cells

Winter

Walter

Min

et al. 2022

Sci Rep

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The fast-firing step commonly applied at the end of solar cell production lines is known to trigger light-induced degradation effects on solar cells made on different silicon materials. In this study, we examine degradation phenomena on high-efficiency solar cells with poly-Si passivating contacts made on Ga-doped Czochralski-grown silicon (Cz-Si) base material under one-sun illumination at elevated temperatures ranging from 80 to 160 °C. The extent of degradation is demonstrated to increase with the applied temperature up to 140 °C. Above 140 °C, the degradation extent decreases with increasing temperature. The degradation of the energy conversion efficiency can be ascribed foremost to a reduction of the short-circuit current and the fill factor and to a lesser extent to a reduction of the open-circuit voltage. The extent of degradation at 140 °C amounts to 0.4%abs of the initial conversion efficiency of 22.1% compared to 0.15%abs at 80 °C. The extent of the efficiency degradation in the examined solar cells is significantly lower (by a factor of ~ 5) compared to solar cells made on B-doped Cz-Si wafers. Importantly, through prolonged illumination at elevated temperatures (e.g. 5 h, 1 sun, 140 °C), an improvement of the conversion efficiency by up to 0.2%abs compared to the initial value is achievable in combination with a permanent regeneration resulting in long-term stable conversion efficiencies above 22%.

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Section: Resultscontrasting

confidence: 72%

“…The (temporary) recovery takes about 15–30 min at 0.5 suns and ~ 44 °C. Details can be found in our recent publication 20 .…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Light and elevated temperature induced degradation and recovery of gallium-doped Czochralski-silicon solar cells

Winter

Walter

Min

et al. 2022

Sci Rep

Self Cite

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Results from an international interlaboratory study on light‐ and elevated temperature‐induced degradation in solar modules

Karas

Repins

Berger

et al. 2022

Progress in Photovoltaics

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This paper reports the results of an international interlaboratory comparison study on light‐ and elevated temperature‐induced degradation (LETID) on crystalline silicon photovoltaic (PV) modules. A large global network of PV module manufacturers and PV testing laboratories collaborated to design a protocol for LETID detection and screen a large and diverse set of prototype modules for LETID. Results across labs indicate the reproducibility of LETID testing is likely within ±1% of maximum power (PMP). In intentionally engineered LETID‐sensitive modules, mean degradation after the prescribed detection stress is roughly 6% PMP. In other module types the LETID sensitivity is smaller, and in some we observe essentially negligible degradation attributable to LETID. In LETID‐sensitive modules, both open‐circuit voltage (VOC) and short‐circuit current (ISC) degrade by a roughly similar magnitude. We observe, as do previous studies, that LETID affects each cell in a module differently. An investigation of the potential mismatch losses caused by nonuniform LETID degradation found that mismatch loss is insignificant compared to the estimated loss of cell ISC, which drives loss of module ISC. Overall, this work has helped inform the creation of a forthcoming standard technical specification for LETID testing of PV modules, IEC TS 63342 ED1, and should aid in the interpretation of results from that and other LETID tests.

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Stability Study of Silicon Heterojunction Solar Cells Fabricated with Gallium‐ and Boron‐Doped Silicon Wafers

et al. 2021

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Herein, a comparison of industrial silicon heterojunction (SHJ) solar cells formed using p‐type (boron‐ or gallium‐doped) Czochralski‐grown silicon (Cz‐Si) wafers is provided. Standard n‐type SHJ solar cells are also fabricated as a reference. Boron‐doped SHJ solar cells are heavily susceptible to boron–oxygen light‐induced degradation (BO‐LID), with an open‐circuit voltage (VOC) reduction of 100 mV in some cells with starting VOC of >720 mV. While an advanced hydrogenation process (AHP) is sufficient to completely stabilize BO‐LID in some cells, resulting in stable VOC of 724 mV, the impact in reducing BO‐LID is variable. This suggests that an AHP alone may not be a reliable method of reducing BO‐LID in industrial SHJ solar cells. In contrast, SHJ solar cells formed using gallium‐doped wafers exhibit VOC > 730 mV and show no degradation during light‐soaking. Yet, the same AHP treatment for gallium‐doped SHJ cells results in a 0.4%abs increase in the conversion efficiency to 22.6% (VOC of 734 mV). The conversion efficiency of the gallium‐doped SHJ solar cells is still lower than the n‐type reference cells, which is largely due to a reduced fill factor (FF). Further work is required to overcome this FF limitation to facilitate high‐efficiency gallium‐doped SHJ solar cells.

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Carrier Lifetime Degradation and Regeneration in Gallium- and Boron-Doped Monocrystalline Silicon Materials

Cited by 21 publications

References 21 publications

Light and elevated temperature induced degradation and recovery of gallium-doped Czochralski-silicon solar cells

Light and elevated temperature induced degradation and recovery of gallium-doped Czochralski-silicon solar cells

Results from an international interlaboratory study on light‐ and elevated temperature‐induced degradation in solar modules

Stability Study of Silicon Heterojunction Solar Cells Fabricated with Gallium‐ and Boron‐Doped Silicon Wafers

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