Light-induced changes in the minority carrier diffusion length of Cu(In,Ga)Se2 absorber material

Heise, Stephan J.; Gerliz, V.; Hammer, Maria S.; Ohland, J.; Keller, Jan; Hammer-Riedel, Ingo

doi:10.1016/j.solmat.2017.01.045

Cited by 37 publications

(32 citation statements)

References 25 publications

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“…The segregation process of Na is independent from the ALE history of the absorber and was also observed on non‐ALE cells. Similar findings are reported in Heise et al and Chen et al after (heat) light soaking of complete devices. In these works, a decreased extension of the space charge region caused by an increased p‐type conductivity or a decreased diffusion length by an additional defect state was found .…”

Section: Resultssupporting

confidence: 90%

“…Similar findings are reported in Heise et al and Chen et al after (heat) light soaking of complete devices. In these works, a decreased extension of the space charge region caused by an increased p‐type conductivity or a decreased diffusion length by an additional defect state was found . Thus, Na segregation after HLS in our case may explain the reduced J SC in consequence of a decreased collection length (space charge region + diffusion length) of charge carriers.…”

Section: Resultssupporting

confidence: 90%

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Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Hölscher

Schneider

Maiberg

et al. 2018

Progress in Photovoltaics

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The impact of air‐light exposure of bare Cu(In,Ga)Se2 layers is investigated by measuring the performance of completed solar cells. Solar cells formed from air‐light–exposed absorbers reveal inferior cell parameters by about 10% regarding open circuit voltage, fill factor, and efficiency compared with cells from nonilluminated absorbers. Time‐dependent and temperature‐dependent open circuit voltage measurements give reasons that the solar cell impairment by air‐light exposure of the bare absorbers is due to interface recombination. Interface states are detected by admittance spectroscopy. Heat‐light soaking of complete solar cells—having formerly degraded interfaces—recovers the solar cell parameters up to the nondegraded levels. Paradoxically, both the air‐light–induced degradation of bare absorbers and the revision of cell parameters after light annealing go along with a light‐induced segregation of sodium at the Cu(In,Ga)Se2 surface and Cu(In,Ga)Se2/CdS interface, respectively.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 90%

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Hölscher

Schneider

Maiberg

et al. 2018

Progress in Photovoltaics

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“…Many published studies have documented the behavior of metastable defects in the CIGS absorber . It is generally accepted that these defects act in two ways, typically both beneficial, when a device is light soaked.…”

Section: Absorber Variationsmentioning

confidence: 99%

Large metastability in Cu (In,Ga)Se₂ devices: The importance of buffer properties

Repins

Glynn

Silverman

et al. 2019

Progress in Photovoltaics

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Some commercial Cu (In,Ga)Se2 (CIGS) modules show large changes in current‐voltage parameters with light soaking. While such changes are not necessarily indicative of a performance problem, the associated uncertainty may be disadvantageous in a highly competitive market. Thus, it is beneficial to understand the origin of large metastabilities in order to define what processing changes might diminish metastability without impacting other desirable aspects of high‐performance devices. This study attempts to reproduce large metastabilities like those in some commercial products both through absorber and buffer processing variations in small devices. While variations of both types were found to affect metastability, only buffer variations could reproduce large metastability in high‐efficiency devices. Device modeling confirms that buffer effects alone are sufficient to explain the large metastability seen in these devices.

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“…In a CdS/CIGS (non alkali‐treated) solar cell, the metastable behavior due to the presence of a vacancy complex (especially V Se – V Cu ) has been suggested . Both the positive and negative effects due to this metastable behavior have been reported . However, in CdS/alkali metal‐treated CIGS solar cells, HLS guarantees an improvement in V OC and FF under the optimized condition .…”

mentioning

confidence: 99%

“…Therefore, an increase in N CV after HLS may have decreased the electric field near the Mo back contact that reduced the carrier collection at long wavelengths. A poor carrier collection in the solar cell by diminishing the electron beam induced current (EBIC) signal toward the Mo side on the CIGS solar cell was observed after HLS treatment . A recent report suggested that the carrier collection efficiency in the solar cell after HLS also depends on the presence of alkali metals near the Mo back contact .…”

mentioning

confidence: 99%

Metastable Behavior on Cesium Fluoride‐Treated Cu(In_1–x,Ga_x)Se₂ Solar Cells

Khatri

Yashiro

Lin

et al. 2020

Physica Rapid Research Ltrs

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Metastable behavior of cesium fluoride (CsF)‐treated Cu(In1–x,Gax)Se2 (CIGS) solar cells is investigated under heat‐light soaking (HLS) and heat‐soaking (HS) treatments. HLS increases open‐circuit voltage, fill factor, efficiency, and net carrier concentration and decreases short‐circuit current density, whereas heat‐soaking treatment acts oppositely. The performance of a CsF postdeposition treatment to CIGS thin film in selenium vapor, and closer to stoichiometry copper content, did not mitigate the open‐circuit voltage improvement after HLS. These results argue the traditional concept of the VSe–VCu divacancy complex for the total beneficial effect of HLS in alkali‐treated CIGS solar cells. The metastable behavior observed in the CsF‐treated devices due to the HLS and HS treatments is explained by the specific behavior of alkali‐containing new compounds at the surface and/or the migration of alkali metals at the surface and bulk regions.

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Light-induced changes in the minority carrier diffusion length of Cu(In,Ga)Se2 absorber material

Cited by 37 publications

References 25 publications

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Large metastability in Cu (In,Ga)Se₂ devices: The importance of buffer properties

Metastable Behavior on Cesium Fluoride‐Treated Cu(In_1–x,Ga_x)Se₂ Solar Cells

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Light-induced changes in the minority carrier diffusion length of Cu(In,Ga)Se2 absorber material

Cited by 37 publications

References 25 publications

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se2 solar cells

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se2 solar cells

Large metastability in Cu (In,Ga)Se2 devices: The importance of buffer properties

Metastable Behavior on Cesium Fluoride‐Treated Cu(In1–x,Gax)Se2 Solar Cells

Contact Info

Product

Resources

About

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Impact of air‐light exposure on the electrical properties of Cu(In,Ga)Se₂ solar cells

Large metastability in Cu (In,Ga)Se₂ devices: The importance of buffer properties

Metastable Behavior on Cesium Fluoride‐Treated Cu(In_1–x,Ga_x)Se₂ Solar Cells