Light-induced degradation variation in industrial multicrystalline PERC silicon solar cells

Lindroos, Jeanette; Zuschlag, Annika; Carstensen, Jürgen; Hahn, Giso

doi:10.1063/1.5049332

Cited by 10 publications

(13 citation statements)

References 16 publications

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“…Finally, Figure C reveals that the degradation is rather uniform laterally in good grain areas, which is characteristic of LeTID . However, defect clusters show slightly stronger LeTID, as reported recently, which is even more pronounced in the acidic‐textured cells (Figure E,F).…”

Section: Resultssupporting

confidence: 89%

Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

Pasanen

Modanese

Vähänissi

et al. 2018

Progress in Photovoltaics

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Light and elevated‐temperature induced degradation (LeTID) is currently a severe issue in passivated emitter and rear cells (PERC). In this work, we study the impact of surface texture, especially a black silicon (b‐Si) nanostructure, on LeTID in industrial p‐type mc‐Si PERC. Our results show that during standard LeTID conditions the b‐Si cells with atomic‐layer‐deposited aluminum oxide (AlOx) front surface passivation show no degradation despite the presence of a hydrogen‐rich AlOx/SiNx passivation stack on the rear. Furthermore, b‐Si solar cells passivated with silicon nitride (SiNx) on the front lose only 1.5%rel of their initial power conversion efficiency, while the acidic‐textured equivalents degrade by nearly 4%rel under the same conditions. Correspondingly, clear degradation is visible in the internal quantum efficiency (IQE) of the acidic‐textured cells, especially in the ~850 to 1100‐nm wavelength range confirming that the degradation occurs in the bulk, while the IQE remains nearly unaffected in the b‐Si cells. The observations are supported by spatially resolved photoluminescence (PL) maps, which show a clear contrast in the degradation behavior of b‐Si and acidic‐textured cells, especially in the case of SiNx front surface passivation. The PL maps also suggest that the magnitude of LeTID scales with surface area of the texture, rather than wafer thickness that was recently reported, although the b‐Si cells are slightly thinner (140 vs 165 μm). The results indicate that b‐Si has a positive impact on LeTID, and hence, benefits provided by b‐Si are not limited only to the excellent optical properties, as commonly understood.

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Section: Resultssupporting

confidence: 89%

Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

Pasanen

Modanese

Vähänissi

et al. 2018

Progress in Photovoltaics

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“…During the editorial process, the reviewers of the manuscript pointed on a difference between locations of the LeTID‐related defects reported in the present work and those presented in the previous publications. Namely, in several publications (see previous studies), it was indicated that the grain boundary (GB) locations are less subjected to the LeTID than the intragrain material, whereas in the present study locations with the higher VSD density were usually degraded more in comparison with the surrounding material. It should be noted that contrary, higher aptitude to LeTID for locations containing dislocations, was also reported previously (see the study by Krauss et al and references therein).…”

Section: Resultsmentioning

confidence: 44%

“…Due to this effect, estimation of recombination activity of GB (and VSD in general) by PL is hampered, and possible changes of GB activity in PL study are particularly smeared. This may be a reason that PL did not detect degradation on GBs in . In contrast, the injection of carriers during the EL is not affected by light scattering.…”

Section: Resultsmentioning

confidence: 94%

Location and Properties of Carrier Traps in mc‐Si Solar Cells Subjected to Degradation at Elevated Temperatures

Mchedlidze

Weber

2019

Physica Status Solidi (a)

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Multi‐crystalline Si (mc‐Si) solar cells subjected to carrier‐induced efficiency degradation at elevated temperatures are studied using deep‐level transient spectroscopy (DLTS), capacitance‐voltage, and electroluminescence (EL) measurements. Commercially available passivated emitter and rear cell (PERC) mc‐Si solar cells are investigated after short annealing in the dark (at T = 200 °C for 20 min), after degradation by a constant forward current at 70 °C, and after regeneration annealing at 200 °C for 20 min. The degradation is detected in situ by EL imaging of the surface of the cell. Several n+p mesa‐diodes, selectively fabricated on the front surface of the solar cell, allow the characterization of locations with various levels of degradation and density of extended defects. The degree of the degradation correlates with the local active boron concentration. At all stages, traps associated with extended defects (i.e., dislocations, grain boundaries, precipitates, etc.) are detected by DLTS, and these traps are not affected by changes in the degree of degradation. Two minority‐carrier traps with energy level positions in the bandgap at Ec −0.19 eV and Ec −0.34 eV are detected only in the degraded solar cells in concentrations that correlate with the local degree of cell degradation.

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“…To analyze the spatially distributed defect density changes in the wafers with the defect‐engineering processes used in this study, relative recombination rate change (RRRC) maps were prepared. This was based on the approach by Lindroos et al., where normalized defect density maps were prepared subtracting the inverse lifetime maps of SiN x :H passivated wafers in different degradation stages . In a simplified approach, here the PL signal is assumed to be proportional to the excess carrier density and the net doping .…”

Section: Resultsmentioning

confidence: 99%

P‐type Upgraded Metallurgical‐Grade Multicrystalline Silicon Heterojunction Solar Cells with Open‐Circuit Voltages over 690 mV

Stefani

Weigand

Wright

et al. 2019

Physica Status Solidi (a)

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Herein, low‐cost p‐type upgraded metallurgical‐grade (UMG) multicrystalline silicon wafers are processed from the edge of the silicon cast using a multi‐stage defect‐engineering approach, incorporating gettering and hydrogenation to improve the wafer quality. Significant reductions in the concentration of interstitial iron and improvements in the bulk lifetime from 15 to 130 µs are observed. Subsequently, all the surface layers are removed and silicon heterojunction solar cells are fabricated. The cells exhibit an efficiency of 18.7%, and open‐circuit voltages over 690 mV is formed using wafers with initial lifetimes of <15 µs. This demonstration of such high voltages, the highest recorded for this material to date, indicates the power of the gettering and hydrogenation processes used and the potential of p‐type UMG silicon to fabricate heterojunction solar cells and other solar cell technologies capable of high open‐circuit voltages.

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Light-induced degradation variation in industrial multicrystalline PERC silicon solar cells

Cited by 10 publications

References 16 publications

Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

Impact of black silicon on light‐ and elevated temperature‐induced degradation in industrial passivated emitter and rear cells

Location and Properties of Carrier Traps in mc‐Si Solar Cells Subjected to Degradation at Elevated Temperatures

P‐type Upgraded Metallurgical‐Grade Multicrystalline Silicon Heterojunction Solar Cells with Open‐Circuit Voltages over 690 mV

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