Interface redox engineering of Cu(In,Ga)Se2 – based solar cells: oxygen, sodium, and chemical bath effects

Kronik, Leeor; Rau, Uwe; Guillemoles, Jean‐François; Braunger, D.; Schock, Hans‐Werner; Cahen, David

doi:10.1016/s0040-6090(99)00768-3

Cited by 99 publications

(74 citation statements)

References 21 publications

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“…This etching of the grain surface is important for making a low-resistance back contact to CdTe [39]. Hence, the grain surface and GB chemistry should be independently tailored for optimal cell performance, as was deduced earlier also for Cu(In,Ga)Se 2 /CdS cells [40].…”

Section: Methodsmentioning

confidence: 81%

How Polycrystalline Devices Can Outperform Single‐Crystal Ones: Thin Film CdTe/CdS Solar Cells

et al. 2004

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Grain boundaries (GBs) participate in the photovoltaic energy conversion process in polycrystalline solar cells as efficient photocurrent collectors and transporters, as shown by high‐ resolution characterization of CdTe GBs in CdTe/CdS cells (see Figure). This suggests that structural defects can be advantageous for device performance, if properly designed, even in devices whose operation is based on physics of ideal, perfect solids.

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Section: Methodsmentioning

confidence: 81%

How Polycrystalline Devices Can Outperform Single‐Crystal Ones: Thin Film CdTe/CdS Solar Cells

et al. 2004

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“…However, this barrier cannot be a general feature of all GBs in high-efficiency CIGS absorbers. The generally benign character of GBs must also embrace beneficial crystallographic GB structures 11,12 and defect chemical passivation of GB defects [18][19][20][21] in order to keep the defect density low.…”

Section: Discussionmentioning

confidence: 99%

“…Especially, the question was discussed whether, and if yes, how GBs can be beneficial for CIGS and CdTe solar cells whereas they are detrimental for most other photovoltaic materials. In addition, there are several models that explain the low electronic activity of GBs in CIGS with the help of arguments concerning beneficial crystallography of GBs, 12 extrinsic defect chemistry based on the beneficial effect of oxygen 18,19 and sodium, 20,21 as well as a self-passivation effect by an internal valence band offset. 13,14 The present work uses two-dimensional numerical simulations of polycrystalline CIGS solar cells to investigate the influence of GBs on their electrical performance.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of carrier collection and recombination at grain boundaries in Cu(In,Ga)Se2 solar cells

Taretto

Rau

2008

Journal of Applied Physics

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Two-dimensional numerical device simulations investigate the influence of grain boundaries ͑GBs͒ on the performance of Cu͑In, Ga͒Se 2 solar cells. We find that the electronic activity of grain boundaries can reduce the efficiency of Cu͑In, Ga͒Se 2 solar cells from 20% to below 12% making proper passivation of GBs a primary requirement for high efficiency. Cell efficiencies larger than 19% require GB defect densities below 10 11 cm −2 . Also, an internal band offset in the valence band due to a Cu-poor region adjacent to the GBs could effectively passivate grain boundaries that are otherwise very recombination active. It is shown that such a barrier must be more than 300 meV high and at least 3 nm wide to virtually suppress all grain boundary recombination. Contrariwise, such a barrier represents an obstacle for hole transport reducing carrier collection across grain boundaries that are not perpendicular to the cell surface. We further find that inverted grain boundaries lead to an accumulation of the short circuit current along the grain boundary, which in certain situations enhances the total short circuit current. However, we do not find any beneficial effect of any type of grain boundaries on the overall cell efficiency.

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“…[15] Other work has shown that O and Na are extrinsically passivating the GBs. [16][17][18] Another possible explanation is attributed to compositional differences at the GBs compared to the gain interior that leads to the formation of a larger hole barrier that repels holes and reduces recombination at the GBs. [19,20] As a result of enhanced charge separation and negligible recombination in the GBs, photogenerated electrons are attracted into the GBs and travel along the GBs towards the CdS and ZnO layers where they are collected.…”

Section: Doi: 101002/adma201103470mentioning

confidence: 99%

Investigating the Role of Grain Boundaries in CZTS and CZTSSe Thin Film Solar Cells with Scanning Probe Microscopy

2012

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Interface redox engineering of Cu(In,Ga)Se2 – based solar cells: oxygen, sodium, and chemical bath effects

Cited by 99 publications

References 21 publications

How Polycrystalline Devices Can Outperform Single‐Crystal Ones: Thin Film CdTe/CdS Solar Cells

How Polycrystalline Devices Can Outperform Single‐Crystal Ones: Thin Film CdTe/CdS Solar Cells

Numerical simulation of carrier collection and recombination at grain boundaries in Cu(In,Ga)Se2 solar cells

Investigating the Role of Grain Boundaries in CZTS and CZTSSe Thin Film Solar Cells with Scanning Probe Microscopy

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