Fundamental Mechanisms Behind the Reverse Characteristic of Cu(In,Ga)Se<sub>2</sub> Solar Cells

Bakker, Klaas; Assen, Suzanne; Rasia, Alix; Barreau, Nicolas; Weeber, Arthur; Theelen, Mirjam

doi:10.1109/jphotov.2022.3196827

Cited by 3 publications

(7 citation statements)

References 15 publications

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“…The data clearly show a linear behaviour above a certain voltage (for 220 K this voltage apparently exceeded the measured range). This indicates that Fowler-Nordheim tunneling dominates the reverse breakdown at higher (negative) voltages which is in agreement with previous reports [6,16]. By using equation ( 1), the barrier height F FN may be extracted from the slope of the linear region in the Fowler-Nordheim plot [22].…”

Section: Intermittent Voltage Sweepssupporting

confidence: 90%

“…Instead, the reverse breakdown in CIGS solar cells is believed to be mainly driven by two tunneling mechanisms [6,16]: (i) tunneling through a triangular barrier at the CIGS/CdS heterointerface (conduction-band spike), which can be described by the Fowler-Nordheim model [17]. (ii) Tunneling via defect states in the band gap, which can be described by the Poole-Frenkel model [18].…”

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

“…where F FN is the height of the barrier, E is the electric field which contains information about the width of the barrier, and C FN is a scaling factor which was introduced by Bakker et al [6] to fit their experimental data. (Further, q is the electric charge, h Planck's constant and m i the effective electron mass in material i.)…”

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

“…Here, the common assumption was made, that the applied voltage V app drops entirely over the buffer layer for all T, so that the electric field may be calculated as E = V app /d CdS (with d CdS the thickness of the buffer layer) [6,16,20]. The data clearly show a linear behaviour above a certain voltage (for 220 K this voltage apparently exceeded the measured range).…”

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

“…That is, on the one hand the cell temperature cannot be assumed to be constant during a reverse IV measurement. But on the other hand the breakdown behaviour is known to be extremely temperature dependent [5,6]: With increasing temperature, the breakdown voltage shifts towards lower (absolute) values. This issue poses a challenge for developing appropriate quantitative models of the reverse breakdown.…”

Section: Introductionmentioning

confidence: 99%

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Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Heise

Komilov²,

Richter³

et al. 2023

EPJ Photovolt.

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When a solar cell is subjected to a negative voltage bias, it locally heats up due to the deposited electrical power. Therefore, every investigation of cell characteristics in the negative voltage regime faces the challenge that the measurement itself changes the state of the cell in a way that is difficult to quantify: On the one hand, the reverse breakdown is known to be strongly temperature dependent. On the other hand, negative voltages lead to metastable device changes which are also very sensitive to temperature. In the current study, we introduce a new approach to suppress this measurement-induced heating by inserting time delays between individual voltage pulses when measuring. As a sample system we use thin-film solar cells based on Cu(In,Ga)Se2 (CIGS) absorber layers. First we verify that with this approach the measurement-induced heating is largely reduced. This allows us to then analyse the impact of the heating on two characteristics of the cells: (i) the reverse breakdown behaviour and (ii) reverse-bias-induced metastable device changes. The results show that minimising the measurement-induced heating leads to a significant increase of the breakdown voltage and effectively slows down the metastable dynamics. Regarding the reverse breakdown, the fundamental tunneling mechanisms that are believed to drive the breakdown remain qualitatively unchanged, but the heating affects the quantitative values extracted for the associated energy barriers. Regarding the reverse-bias metastability, the experimental data reveal that there are two responsible mechanisms that react differently to the heating: Apart from a charge redistribution at the front interface due to the amphoteric (VSe–VCu) divacancy complex, the modification of a transport barrier is observed which might be caused by ion migration towards the back interface. The findings in this study demonstrate that local sample heating due to reverse-bias measurements can have a notable impact on device behaviour which needs to be kept in mind when developing models of the underlying physical processes.

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Section: Intermittent Voltage Sweepssupporting

confidence: 90%

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

Section: Intermittent Voltage Sweepsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Heise

Komilov²,

Richter³

et al. 2023

EPJ Photovolt.

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Post‐Mortem Analysis of Building‐Integrated Flexible Thin Film Modules

Kingma,

Kirchner Sala,

Simeonov

et al. 2024

Progress in Photovoltaics

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Flexible, lightweight thin film (TF) photovoltaic (PV) modules offer a unique opportunity for integration into non‐planar surfaces unable to support heavy weights. While such applications increase the potential for PV in urban areas, the reliability implications are yet to be investigated. Here, prototypes of corrugated rooftiles with integrated Cu (In,Ga)Se2 (CIGS) modules were investigated after 3 years of outdoor operation. Their performance before and after the outdoor exposure was compared and defects were localized. An unpackaging method was developed, allowing access to the solar cells for more detailed characterization of present defects without causing additional damage or changes to existing defects. To our knowledge, this was the first time such an unpackaging method was successfully applied to flexible TF PV modules. The relative efficiency loss ranged from 17% to 43%, mostly due to short‐circuit current (ISC) loss and series resistance (RS) increase. The predominant cause of the RS increase was the delamination at the interconnects, ascribed to thermomechanical stresses caused by outdoor temperature fluctuations. The ISC loss was mainly caused by localized delamination of CIGS from the molybdenum (Mo) back‐contact. The occurrence of such delaminated areas pointed to presence of high local stresses during outdoor operation, possibly due to thermal fluctuations, applied deformation and/or mechanical impact. Two other types of delamination defects were found with no observable impact on performance. These results show the necessity for further optimization in the material choice and processing of TF flexible modules, to avoid mechanical stress related failures upon integration into curved surfaces.

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Effects of partial shading and temperature-dependent reverse bias behaviour on degradation in perovskite photovoltaic modules

Tayagaki,

Kobayashi,

Yamamoto

et al. 2025

Solar Energy Materials and Solar Cells

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Fundamental Mechanisms Behind the Reverse Characteristic of Cu(In,Ga)Se₂ Solar Cells

Cited by 3 publications

References 15 publications

Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Post‐Mortem Analysis of Building‐Integrated Flexible Thin Film Modules

Effects of partial shading and temperature-dependent reverse bias behaviour on degradation in perovskite photovoltaic modules

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Fundamental Mechanisms Behind the Reverse Characteristic of Cu(In,Ga)Se2 Solar Cells

Cited by 3 publications

References 15 publications

Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Reverse-bias behaviour of thin-film solar cells: effects of measurement-induced heating

Post‐Mortem Analysis of Building‐Integrated Flexible Thin Film Modules

Effects of partial shading and temperature-dependent reverse bias behaviour on degradation in perovskite photovoltaic modules

Contact Info

Product

Resources

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Fundamental Mechanisms Behind the Reverse Characteristic of Cu(In,Ga)Se₂ Solar Cells