Secondary-Phase-Assisted Grain Boundary Migration in 
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Li, Chen; Sanli, Ekin Simsek; Barragan-Yani, Daniel; Stange, Helena; Heinemann, Marc Daniel; Greiner, D.; Sigle, Wilfried; Mainz, Roland; Albe, Karsten; Abou‐Ras, Daniel; Aken, Peter A. van

doi:10.1103/physrevlett.124.095702

Cited by 5 publications

(4 citation statements)

References 39 publications

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“…The Cu-Se phase at grain boundaries plays an important role in grain growth in CIGS thin films [63] (see section 3.3). We hypothesize that because Cu-Se can penetrate deep into CIS layers (owing to better lattice match with CIS) but remains on the surface of CGS layers [64], the annihilation of stacking faults is more effective and thus the defect density is lower for CIS than for CGS [65].…”

Section: Point Defects In Cigsmentioning

confidence: 99%

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CIGS photovoltaics: reviewing an evolving paradigm

Stanbery¹,

Abou‐Ras²,

Yamada³

et al. 2021

J. Phys. D: Appl. Phys.

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Copper indium selenide chalcopyrite-structure alloys with gallium (CIGS) are unique among the highest performing photovoltaic (PV) semiconductor technologies. They are structurally disordered, nonstoichiometric materials that have been engineered to achieve remarkably low bulk nonradiative recombination levels. Nevertheless, their performance can be further improved. This review adopts a fundamental thermodynamic perspective to comparatively assess the root causes of present limitations on CIGS PV performance. The topics of selectivity and passivation of contacts to CIGS and its multinary alloys are covered, highlighting pathways to maximizing the electrochemical potential between those contacts under illumination. An overview of absorber growth methods and resulting properties is also provided. We recommend that CIGS researchers consider strategies that have been successfully implemented in the more mature wafer-based GaAs and Si PV device technologies, based on the paradigm of an idealized PV device design using an isotropic absorber with minimal nonradiative recombination, maximal light trapping, and both electron-selective and hole-selective passivated contacts. We foresee that CIGS technology will reach the 25% efficiency level within the next few years through enhanced collection and reduced recombination. To significantly impact power-generation applications, cost-effective, manufacturable solutions are also essential.

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Section: Point Defects In Cigsmentioning

confidence: 99%

“…Recent complementary in situ STEM studies of the secondstage transition from copper-deficient CIS to a copper-rich material [63,158] clearly demonstrate that grain boundaries migrate during heating. Grains with lower planar defect densities consume those with more defects.…”

Section: Reactive Codeposition Absorber Synthesismentioning

confidence: 99%

CIGS photovoltaics: reviewing an evolving paradigm

Stanbery¹,

Abou‐Ras²,

Yamada³

et al. 2021

J. Phys. D: Appl. Phys.

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“…The transition may result in an increase in average grain size and the annihilation of defects. [25,26] In contrast, the solution-processed chalcopyrite film is achieved by coating a precursor solution (which includes Cu, In, Ga, and S/Se source), followed by an annealing and selenization process. [27] The chalcopyrite phase is directly formed during the thermal annealing process due to the chemical reaction in the precursor solution.…”

Section: Introductionmentioning

confidence: 99%

Over 16% Efficient Solution‐Processed Cu(In,Ga)Se₂ Solar Cells via Incorporation of Copper‐Rich Precursor Film

Gao

Yuan

Zhou

et al. 2022

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Solution processing of Cu(In,Ga)Se2 (CIGS) absorber is a highly promising strategy for a cost‐effective CIGS photovoltaic device. However, the device performance of solution‐processed CIGS solar cells is still hindered by the severe non‐radiative recombination resulting from deep defects and poor crystal quality. Here, a simple and effective precursor film engineering strategy is reported, where Cu‐rich (CGI >1) CIGS layer is incorporated into the bottom of the CIGS precursor film. It has been discovered that the incorporation of the Cu‐rich CIGS layer greatly improves the absorber crystallinity and reduces the trap state density. Accordingly, more efficient charge generation and charge transfer are realized. As a result of systematic processing optimization, the champion solution‐processed CIGS device delivers an improved open‐circuit voltage of 656 mV, current density of 33.15 mA cm−2, and fill factor of 73.78%, leading to the high efficiency of 16.05%.

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“…[ 6 ] The Cu‐poor/Cu‐rich transition is accompanied by structural and morphological changes that include an increase in grain size, recrystallization (stress relaxation), and a decrease in stacking fault density and planar defects. [ 8 ] In 2019, Feurer et al reported that Urbach energies decreased from ≈20 to 16 meV by increasing the Cu concentration in the absorber films (from [Cu]/[In] ≈ 0.88 to 0.95).7 Record PCEs of 19.2% were demonstrated for CISSe devices with a near stoichiometric absorber composition, having an external quantum efficiency (EQE) determined minimum bandgap ( E g ) of 1.0 eV. Notably, however, in terms of film processing, the absorber growth process for vacuum‐ and IDR‐based absorbers is fundamentally different, i.e., a single‐step deposition (elemental evaporation rates and substrate temperature are adjusted to tailor grain growth and bandgap gradients) versus two‐step process (nearly all the constituent elements (Cu, In, and S/Se) mixed in atomic compositions, deposited, and thermally treated in a chalcogen environment for grain growth).…”

Section: Introductionmentioning

confidence: 99%

Over 13% Efficient, Ambient Air‐Processed CuIn(S,Se)₂ Solar Cells via Compositional Engineering of Molecular Inks

2023

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A dimethylformamide (DMF) and thiourea (TU)‐based ink deposition route is used to fabricate narrow bandgap (≈1.0 eV) CuIn(S,Se)2 (CISSe) films with Cu‐poor ([Cu]/[In] = 0.85), stoichiometric ([Cu]/[In] = 1.0), and Cu‐rich ([Cu]/[In] = 1.15) compositions for photovoltaic applications. Characterization of KCN‐ or (NH4)2S‐treated Cu‐rich absorber films using X‐ray diffraction and scanning electron microscopy confirms the removal of copper‐selenide phases from the film surface, while electron backscatter diffraction measurements and depth‐dependent energy‐dispersive X‐ray spectroscopy indicate remnant copper‐selenides in the absorber layer bulk. Contrary to best practice for vacuum‐processed cells, optimum [Cu]/[In] ratios appear to be stoichiometric, rather than Cu‐poor, in DMF–TU‐based CISSe devices. Accordingly, stoichiometric film compositions yield large‐grained (≈2 μm) absorber layers with smooth absorber surfaces (root mean square roughness <20 nm) and active area device efficiencies of 13.2% (without antireflective coating). Notably, these devices reach 70.0% of the Shockley–Queisser limit open‐circuit voltage (i.e., 526 mV at Eg of 1.01 eV), which is among the highest for ink‐based CISSe devices.

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Secondary-Phase-Assisted Grain Boundary Migration in CuInSe2

Cited by 5 publications

References 39 publications

CIGS photovoltaics: reviewing an evolving paradigm

CIGS photovoltaics: reviewing an evolving paradigm

Over 16% Efficient Solution‐Processed Cu(In,Ga)Se₂ Solar Cells via Incorporation of Copper‐Rich Precursor Film

Over 13% Efficient, Ambient Air‐Processed CuIn(S,Se)₂ Solar Cells via Compositional Engineering of Molecular Inks

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Secondary-Phase-Assisted Grain Boundary Migration in CuInSe2

Cited by 5 publications

References 39 publications

CIGS photovoltaics: reviewing an evolving paradigm

CIGS photovoltaics: reviewing an evolving paradigm

Over 16% Efficient Solution‐Processed Cu(In,Ga)Se2 Solar Cells via Incorporation of Copper‐Rich Precursor Film

Over 13% Efficient, Ambient Air‐Processed CuIn(S,Se)2 Solar Cells via Compositional Engineering of Molecular Inks

Contact Info

Product

Resources

About

Over 16% Efficient Solution‐Processed Cu(In,Ga)Se₂ Solar Cells via Incorporation of Copper‐Rich Precursor Film

Over 13% Efficient, Ambient Air‐Processed CuIn(S,Se)₂ Solar Cells via Compositional Engineering of Molecular Inks