Improved CIGS modules by KF post deposition treatment and reduced cell-to-module losses

Lundberg, Olle; Wallin, Erik; Gusak, Viktoria; Södergren, Sven; Chen, Si; Lotfi, Sara; Chalvet, Francis; Malm, Ulf; Kaihovirta, Nikolai; Mende, Patrick; Jaschke, G.; Kratzert, P.; Joel, Jonathan; Skupinski, Marek; Lindberg, Pia; Jarmar, Tobias; Lundberg, Juhan; Mathiasson, Johan; Stolt, Lars

doi:10.1109/pvsc.2016.7749824

Cited by 13 publications

(17 citation statements)

References 4 publications

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“…In fact, 6 of the last 8 world record CIGS efficiencies have used a KF PDT, advancing the record efficiency from 20.3% to 22.6% in approximately 3.5 years. KF postdeposition treatment successes in the laboratory have now been extended to commercially relevant chalcogenized CIGS absorbers and full size (0.75 m 2 ) modules . Early studies of K in CIGS showed similarities to Na—primarily modifying grain interior (GI) and grain boundary (GB) defect concentrations and improving performance through increasing carrier concentration .…”

Section: Introductionmentioning

confidence: 99%

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

Muzzillo

Poplawsky

Tong

et al. 2018

Progress in Photovoltaics

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RESEARCH AND APPLICATIONSwileyonlinelibrary.com/journal/progressinphotovoltaics PHOTOVOLTAICS Research and ApplicationsProgress in Photovoltaics offers a prestigious forum for reporting advances in this rapidly developing technology, aiming to reach all interested professionals, researchers and energy policy-makers.The key criterion is that all papers submitted should report substantial "progress" in photovoltaics.Papers are encouraged that report substantial "progress" such as gains in independently certified solar cell efficiency, eligible for a new entry in the journal's widely referenced Solar Cell Efficiency Tables.Examples of papers that will not be considered for publication are those that report development in materials without relation to data on cell performance, routine analysis, characterisation or modelling of cells or processing sequences, routine reports of system performance, improvements in electronic hardware design, or country programs, although invited papers may occasionally be solicited in these areas to capture accumulated "progress".Systems papers will only be considered in exceptional cases, such as where new developments in system applications have produced substantial progress in energy yield or reliability.Prospective authors are encouraged to consider the degree to which their contributions report significant progress in the field and to consider other means of publication for those not meeting the high standard required by Progress in Photovoltaics.

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Section: Introductionmentioning

confidence: 99%

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

Muzzillo

Poplawsky

Tong

et al. 2018

Progress in Photovoltaics

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“…to commercially-relevant chalcogenized CIGS absorbers, [12] full size (0.75 m 2 ) modules, [13] and Cd-free Zn(O,S) buffers. [2,12,22] Although the mechanisms responsible for these efficiency improvements are not clear, the KF PDT has been associated with multiple phenomena: increased hole concentration (e.g., by consuming InCu compensating donors to produce KCu neutral defects [23] ), [5,7,8,11,14,15,19,[24][25][26][27] decreased hole concentration (by consuming NaCu to produce InCu compensating donors, [1] or by forming (K-K)Cu dumbbell interstitial donors [28] ), [1,8,10,16] Na depletion or formation of soluble Na chemical(s), [1,5,7,8,10,13,14,25,26,29,30] Ga depletion at the surface, [1, 8, 10, 13-15, 29, 31, 32] Cu depletion at the surface [7,13,15,18,20] resulting in better near-surface inversion [1,8,10,16,33] or decreased valence band energy,…”

Section: Introductionmentioning

confidence: 99%

Surface and bulk effects of K in highly efficient Cu1-xKxInSe2 solar cells

Muzzillo

Mansfield

et al. 2018

Solar Energy Materials and Solar Cells

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To advance knowledge of K bonding in Cu(In,Ga)(Se,S)2 (CIGS) photovoltaic (PV) absorbers, recent Cu-K-In-Se phase growth studies have been extended to PV performance. First, the effect of distributing K throughout bulk Cu1-xKxInSe2 absorbers at low K/(K+Cu) compositions (0 ≤ x ≤ 0.30) was studied.Efficiency, open-circuit voltage (VOC), and fill factor (FF) were greatly enhanced for x ~ 0.07, resulting in an officially-measured 15.0%-efficient solar cell, matching to the world record CuInSe2 efficiency. The improvements were a result of reduced interface and bulk recombination, relative to CuInSe2 (x ~ 0). However, higher x compositions had reduced efficiency, short-circuit current density (JSC), and FF due to greatly increased interface recombination, relative to the x ~ 0 baseline. Next, the effect of confining K at the absorber/buffer interface at high K/(K+Cu) compositions (0.30 ≤ x ≤ 0.92) was researched. Previous work showed that these surface layer growth conditions produced CuInSe2 with a large phase fraction of KInSe2. After optimization (75 nm surface layer with x ~ 0.41), these KInSe2 surface samples exhibited increased efficiency (officially 14.9%), VOC, and FF as a result of decreased interface recombination. The KInSe2 surfaces had features similar to previous reports for KF post-deposition treatments (PDTs) used in world record CIGS solar cells-taken as indirect evidence that KInSe2 can form during these PDTs. Both the bulk and surface growth processes greatly reduced interface recombination. However, the KInSe2 surface had higher K levels near the surface, greater lifetimes, and increased inversion near the buffer interface, relative to the champion bulk CKIS absorber. These characteristics demonstrate that K may benefit PV performance by different mechanisms at the surface and in the absorber bulk.Graphical abstract:

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“…Cu(In,Ga)Se 2 (CIGSe) thin film based photovoltaic technology has reached an outstanding level of performance at the laboratory scale. In 2016, Jackson et al reported a 22.6% independently certified champion efficiency and several academic labs, as well as companies over the world, do master the fabrication of small scale devices demonstrating more than 20% energy conversion efficiency . This recent performance breakthrough was made possible thanks to the treatment of completed absorbers with heavy‐alkali fluoride, namely KF or RbF.…”

Section: Introductionmentioning

confidence: 99%

High Efficiency Solar Cell Based on Full PVD Processed Cu(In,Ga)Se₂/CdIn₂S₄ Heterojunction

et al. 2017

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The original goal of our study is to synthesize by co-evaporation the phase that could be formed at the interface between polycrystalline p-Cu(In,Ga)Se 2 treated with KF and n-CdS. Hence, a new buffer layer, CdIn 2 S 4 (C24), deposited by co-evaporation is presented for the use in thin film solar cells, exhibiting device efficiencies as high as 16.2%, comparable to that obtained on a reference standard CdS-buffered device. The physico-chemical and optical properties of close to stoichiometry 400 nm-thick films of C24 show similar properties to what has been reported in the literature for single crystals. The layer stack used for solar cells is investigated by transmission electron microscopy, showing the formation of an ultrathin Cd-deficient C24 layer at the CIGSe/C24 interface, while a clear lattice match is observed at the C24/ZnO interface. Advanced electrical characterizations of the devices suggest that the output voltage and fill factor of the solar cells based on Cu(In,Ga)Se 2 /(PVD)C24 are limited by tunneling-enhanced recombination through extended band tail states. These results open new routes to explain the superiority of wet processes used for the junction formation compared to vacuum-based approaches.

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Improved CIGS modules by KF post deposition treatment and reduced cell-to-module losses

Cited by 13 publications

References 4 publications

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

Surface and bulk effects of K in highly efficient Cu1-xKxInSe2 solar cells

High Efficiency Solar Cell Based on Full PVD Processed Cu(In,Ga)Se₂/CdIn₂S₄ Heterojunction

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Improved CIGS modules by KF post deposition treatment and reduced cell-to-module losses

Cited by 13 publications

References 4 publications

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe2 solar cells

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe2 solar cells

Surface and bulk effects of K in highly efficient Cu1-xKxInSe2 solar cells

High Efficiency Solar Cell Based on Full PVD Processed Cu(In,Ga)Se2/CdIn2S4 Heterojunction

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Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

Revealing the beneficial role of K in grain interiors, grain boundaries, and at the buffer interface for highly efficient CuInSe₂ solar cells

High Efficiency Solar Cell Based on Full PVD Processed Cu(In,Ga)Se₂/CdIn₂S₄ Heterojunction