Acceleration and mitigation of carrier-induced degradation in p-type multi-crystalline silicon

Payne, D.N.; Chan, Catherine; Hallam, Brett; Hoex, Bram; Abbott, Malcolm; Wenham, Stuart; Bagnall, Darren M.

doi:10.1002/pssr.201510437

Cited by 75 publications

(38 citation statements)

References 16 publications

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“…We note here that regeneration in the qm‐PERCs shows similarity to LeTID in its temperature‐dependent behavior. Payne et al have reported that regeneration timescale of LeTID can be accelerated from between tens to hundreds of minutes to less than ten by increasing the temperature from 140 to 250 °C. This is comparable to the increase in the rate of regeneration in the qm‐Si PERC cells when temperature is increased from 150 to 210 °C.…”

Section: Resultsmentioning

confidence: 99%

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Vahlman¹,

Wagner²,

Wolny³

et al. 2017

Physica Status Solidi (a)

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High-efficiency solar cell designs such as the passivated emitter and rear cell (PERC) raise the quality requirements for silicon substrates, favoring monocrystalline materials. Seedcast quasi-monocrystalline silicon (qm-Si) is a promising alternative for Czochralski (Cz) Si with potential benefits of lower cost and reduced energy footprint. However, the purity and crystalline quality of qm-Si is not on par with Cz-Si, which can cause efficiency losses for example in the form of light-induced degradation (LID). In this contribution, we study the LID phenomena that can be present in qm-Si PERC solar cells, and compare them to the Cz-Si PERC. Degradation and regeneration are analyzed especially from the viewpoint of Cu impurity, which has until very recently been omitted as a source of LID for this device type. Subsequently, differences in LID behavior between qm-Si and Cz-Si are investigated considering the density of dislocations in the bulk. The results imply that slurry-based wafer slicing may introduce contamination that is capable of causing considerable LID in PERC devices fabricated of Si with inherently high defect density.

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Section: Resultsmentioning

confidence: 99%

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Vahlman¹,

Wagner²,

Wolny³

et al. 2017

Physica Status Solidi (a)

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“…The degradation and subsequent regeneration rates are sped‐up with increasing temperature, leading to the widely used terminology to describe this phenomenon, light and elevated temperature induced degradation (LeTID). The phenomenon is also referred to in the literature as mc‐Si LID (light‐induced degradation), and mc‐Si CID (carrier‐induced degradation), since, the degradation is triggered through carrier‐injection from either light or current . The degradation will be referred to as mc‐Si CID in this work.…”

mentioning

confidence: 99%

“…Introduction : In 2012, multi‐crystalline silicon (mc‐Si) passivated emitter and rear cells (PERC) were shown to suffer from strong light‐induced degradation effects, and this has been the focus of many subsequent studies . The degradation and subsequent regeneration rates are sped‐up with increasing temperature, leading to the widely used terminology to describe this phenomenon, light and elevated temperature induced degradation (LeTID).…”

mentioning

confidence: 99%

Modulation of Carrier‐Induced Defect Kinetics in Multi‐Crystalline Silicon PERC Cells Through Dark Annealing

et al. 2017

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In this letter, we report on significant changes caused after dark annealing to the kinetics of the carrier‐induced defect, present in p‐type multi‐crystalline silicon PERC cells. The characteristic shapes of the degradation and regeneration curves under light soaking at 75 °C are dramatically altered, depending on the temperature of an initial dark anneal on the non‐degraded cell. Dark annealing for a fixed time (2.5 h) at temperatures of 200 °C or below, is found to accelerate both the subsequent degradation and regeneration rate and the degradation severity, while at higher temperatures it appears that a possible second defect with a significantly longer degradation and regeneration rate is activated. Through a further increase of the dark annealing temperature, the magnitude of this slow degradation is suppressed. This data provides essential information into the role that thermal history plays in the behavior of the still unidentified defect or defects, which is crucial for future studies of the degradation and methods to mitigate it.

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“…Introduction : Thermal processes applied after or as an extension to the co‐firing of screen‐printed solar cells are becoming increasingly common as steps for gettering or passivating defects, or for suppressing carrier‐induced degradation (CID) . Industrial solutions for mitigating CID caused by the boron‐oxygen (BO) defect in Czochralski (Cz) grown silicon are now available, however CID caused by the still unknown defect present in multi‐crystalline silicon (mc‐Si) remains a significant problem, causing relative power losses of typically 8–12% .…”

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confidence: 99%

Instability of Increased Contact Resistance in Silicon Solar Cells Following Post‐Firing Thermal Processes

et al. 2017

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Recently, there have been reports of increased series resistance as a consequence of thermal processes applied after the co‐firing of screen‐printed silicon solar cells. A previous observation of this effect on very heavily diffused emitters concluded that the increased series resistance is the result of a thickening of the glass layer surrounding silver crystallites at the Ag‐Si interface. Here, large increases in the front silver contact resistance after particular thermal anneals are reported that have been used to mitigate carrier‐induced degradation (CID) in multi‐crystalline solar cells that cannot be fully explained by a thickening of the glass layer. Remarkably, under certain conditions the contact resistance immediately after annealing is found to be unstable − decreasing when a forward current is applied to the solar cell, and gradually increasing again once the forward current is removed. It is speculated that the movement of charged particles, most likely hydrogen, could be the cause of this instability.

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Acceleration and mitigation of carrier-induced degradation in p-type multi-crystalline silicon

Cited by 75 publications

References 16 publications

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Light‐induced degradation in quasi‐monocrystalline silicon PERC solar cells: Indications on involvement of copper

Modulation of Carrier‐Induced Defect Kinetics in Multi‐Crystalline Silicon PERC Cells Through Dark Annealing

Instability of Increased Contact Resistance in Silicon Solar Cells Following Post‐Firing Thermal Processes

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