Persistent Photoconductivity in Polycrystalline Cu(In,Ga)Se&lt;sub&gt;2&lt;/sub&gt; Thin Films: Experiment Versus Theoretical Predictions

Macielak, K.; Maciaszek, M.; Igalson, M.; Zabierowski, P.; Barreau, Nicolas

doi:10.1109/jphotov.2015.2423491

Cited by 18 publications

(6 citation statements)

References 18 publications

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“…The metastabilities are explained by the amphoteric character of the V Se ‐ V Cu complex in CIGS, which is a negative‐U center and can act either as a compensating shallow donor or a shallow acceptor . If we assume a CIGS layer with a shallow acceptor density of N sh and a defect complex density of N T , the free‐hole density can be expressed as p = N sh + N T (2 f A − 1), where f A is the fraction of the defect complex in the acceptor configuration . The transition between the different configurations requires simultaneous capture or emission of 2 free carriers (electron or hole) and lattice relaxations together with thermal activation over an energy barrier.…”

Section: Introductionmentioning

confidence: 99%

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

Koida

Nishinaga

Ueno

et al. 2018

Progress in Photovoltaics

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We studied the impacts of front contact layers composed of transparent conducting oxide (TCO) and transparent oxide semiconductor (TOS) layers on the performance of Cu(In,Ga)Se 2 (CIGS) solar cells with glass/Mo/CIGS/CdS/TOS/TCO in relaxed and metastable states. After annealing under illumination, the CIGS solar cells with KF and NaF postdeposition treatments exhibited metastable increases in open-circuit voltage, fill factor, and the resulting conversion efficiency with a metastable decrease in short-circuit current density. These are partly attributed to an increase in metastable acceptor density in the CIGS layers, being stable for a day even at room temperature, with a reduced space charge width. We found that the net acceptor density evaluated by capacitance-voltage measurements largely varied depending on the TOS/TCO layers, whereas the open-circuit voltage was identical. On the other hand, no significant differences in both the net acceptor density and open-circuit voltage were observed regardless of the TOS/TCO layers in the relaxed state produced by annealing in the dark. The results suggest that the CdS/CIGS heterojunction can no longer be treated as an n + /p junction in the metastable state and that the evaluated acceptor density was apparent values with large difference originating from different potential distribution in the CdS layer, which is related to the TOS/CdS and TCO/CdS junctions. In addition, the TOS/TCO layers largely affected the short-circuit current density owing to their optical constants and film thicknesses. The presented results highlight the importance of the design of CdS/TOS/TCO layers in solar cells operated in metastable states.

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Section: Introductionmentioning

confidence: 99%

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

Koida

Nishinaga

Ueno

et al. 2018

Progress in Photovoltaics

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“…In polycrystalline films also this effect is observed. An overview over Cu(In, Ga)Se 2 thin films [129] observed as a function of temperature and light intensity. To have a better idea on this behavior they evaluated the amount of the photo-excited electrons after the light is switched off.…”

Section: Miscellaneous Materialsmentioning

confidence: 99%

A review on realizing the modern optoelectronic applications through persistent photoconductivity

Sumanth¹,

Ganapathi²,

Rao³

et al. 2022

J. Phys. D: Appl. Phys.

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Optoelectronic devices are becoming increasingly important due to their compatibility with CMOS fabrication technology and their superior performance in all dimensions compared to currently available devices. Numerous modern applications are formulated based on various aspects of optoelectronic materials and devices, such as artificial intelligence, optical memory, optoelectronic synapses, humanoid-photodetectors, holography, solar cells, charge storage devices, bio-electronic devices, and so on. Persistent photoconductivity (PPC), an optoelectronic phenomenon that has piqued the scientific community's interest, is a novel approach to these modern applications. In this article, we highlighted the use of PPC in a variety of emerging optoelectronic applications. PPC is a light-induced mechanism that persists after light excitation is terminated, i.e., the response does not stop immediately but remains available for a period of time. In recent years, the time duration over which the response after turning off the illumination is available has been proposed for a variety of applications. PPC has primarily been explored from a theoretical point of view, with the application component being largely ignored. Very recently, the scientific community has started exploring the possible applications pertaining to PPC such as optoelectronic synapses, holography, optical memory, bioelectronics, and artificial intelligence. Depending on the nature of the material and the type of model used in the application, a variety of mechanisms can be used to modulate the charge trapping and de-trapping methodologies for a specific application. This topical review summarizes the origins of PPC, its control mechanism, and recent advances in a variety of materials such as metal oxides, superconductors, nanofibers, 2D-semiconductors, alloys, nitrides, organic materials, topological insulators, and so on. In addition, the paper has carefully explored the development of next-generation optoelectronic applications designed for industry 4.0 leveraging the PPC phenomenon.

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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%

“…Voltage metastability in CIGS devices A, for different buffer types with mean value marked as "X" and B, as a function of light soaking time for a typical sample set made on one absorber piece 4 | ABSORBER VARIATIONS Many published studies have documented the behavior of metastable defects in the CIGS absorber. 3,10,11,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] It is generally accepted that these defects act in two ways, typically both beneficial, when a device is light soaked. In the bulk, light soaking puts defects into an acceptor state, moving the Fermi level toward the valence band edge and thus increasing the built-in potential.…”

Section: Figurementioning

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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Persistent Photoconductivity in Polycrystalline Cu(In,Ga)Se<sub>2</sub> Thin Films: Experiment Versus Theoretical Predictions

Cited by 18 publications

References 18 publications

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

A review on realizing the modern optoelectronic applications through persistent photoconductivity

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

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Persistent Photoconductivity in Polycrystalline Cu(In,Ga)Se<sub>2</sub> Thin Films: Experiment Versus Theoretical Predictions

Cited by 18 publications

References 18 publications

Impact of front contact layers on performance of Cu(In,Ga)Se2 solar cells in relaxed and metastable states

Impact of front contact layers on performance of Cu(In,Ga)Se2 solar cells in relaxed and metastable states

A review on realizing the modern optoelectronic applications through persistent photoconductivity

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

Contact Info

Product

Resources

About

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

Impact of front contact layers on performance of Cu(In,Ga)Se₂ solar cells in relaxed and metastable states

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