Atomic Layer Deposited Aluminum Oxide for Interface Passivation of Cu<sub>2</sub>ZnSn(S,Se)<sub>4</sub> Thin‐Film Solar Cells

Lee, Yun Seog; Gershon, Talia; Todorov, Teodor K.; Wang, Wei; Winkler, M.; Hopstaken, Marinus; Gunawan, Oki; Kim, Jeehwan

doi:10.1002/aenm.201600198

Cited by 90 publications

(77 citation statements)

References 29 publications

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“…Since its first release in 2009, the power conversion efficiency (PCE) of this device has been improved from 3.8 to over 22.1%, with the sandwiched structure of mesoporous or planar electron‐transport layer (ETL)/photoactive layer/hole‐transport layer (HTL). Benefiting from their excellent band alignment, the PSCs show much lower photon energy loss with a relative large ratio of about 0.80 for open‐circuit voltage ( V oc )/band gap ( E g ), in comparison to the typical value of 0.60 for other types of solar cells . The reported V oc of CH 3 NH 3 PbI 3 /spiro‐OMeTAD based PSCs is close to its theoretical value of 1.33 V according to Shockley–Queisser limitation …”

Section: Introductionsupporting

confidence: 68%

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

et al. 2017

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Metallic nanoparticles (NPs) exhibit a surface plasmon resonance (SPR) and can be incorporated into perovskite solar cells (PSCs) to improve cell performance. However, the incorporation of Au NPs in bulk films of PSCs requires large concentration to keep interval distance and would cause worse device performance. In this work, a universal strategy for significant increasing power conversion efficiency (PCE) of PSCs through incorporating high aspect ratio Au nanorods (NRs)@SiO2 into perovskite/spiro‐OMeTAD interface is demonstrated. The key feature of this approach is that we can take advantage of the SPR at a lower concentration and the Au NRs have larger light scattering section than AuNPs. It is found that the SPR and scattering effect of Au NRs lead to a broad enhancement of photon absorption. Furthermore, a superior enhanced charge separation process in the Au NRs incorporated device is also observed. Benefitting from this cooperative plasmonic effect of Au NRs in optical and electrical aspects, both short‐circuit current density and open‐circuit voltage are improved, resulting in the new device delivering a PCE up to 17.39% from 14.39%. This result further supports that Au NRs can play a more effective SPR effect at perovskite/spiro‐OMeTAD interface, rather than incorporating them into bulk films.

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Section: Introductionsupporting

confidence: 68%

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

et al. 2017

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“…Broad emission is typical of Cu-poor CIGS polycrystalline solar cells, [59][60][61] however, for the case of the reference solar cell, the luminescence is significantly broader than that of the passivated cell. [64][65][66][67][68] However, a direct comparison of PL intensity from different samples should be done with caution due to the necessarily different optical alignments despite nominally equivalent experimental conditions and as in this work we do not have those capabilities and we do not perform that comparison here. [62,63] Regarding the passivated solar cell, the full width at half maximum (FWHM) is significantly lower (≈61 meV) than that of the reference solar cell (≈96 meV).…”

Section: Photoluminescencementioning

confidence: 99%

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

Salomé

Vermang

Ribeiro‐Andrade

et al. 2017

Adv Materials Inter

110

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Thin film solar cells based in Cu(In,Ga)Se2 (CIGS) are among the most efficient polycrystalline solar cells, surpassing CdTe and even polycrystalline silicon solar cells. For further developments, the CIGS technology has to start incorporating different solar cell architectures and strategies that allow for very low interface recombination. In this work, ultrathin 350 nm CIGS solar cells with a rear interface passivation strategy are studied and characterized. The rear passivation is achieved using an Al2O3 nanopatterned point structure. Using the cell results, photoluminescence measurements, and detailed optical simulations based on the experimental results, it is shown that by including the nanopatterned point contact structure, the interface defect concentration lowers, which ultimately leads to an increase of solar cell electrical performance mostly by increase of the open circuit voltage. Gains to the short circuit current are distributed between an increased rear optical reflection and also due to electrical effects. The approach of mixing several techniques allows us to make a discussion considering the different passivation gains, which has not been done in detail in previous works. A solar cell with a nanopatterned rear contact and a 350 nm thick CIGS absorber provides an average power conversion efficiency close to 10%.

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“…In this figure, both CZTS-3cycles and CZTS-5cycles show more hydrogen at the surface and heterointerface than that of the reference. [14] In order to confirm whether hydrogen is effectively involved in the surface passivation, we performed Kelvin probe force microscopy (KPFM) to observe spatial surface potential mappings of the associated CZTS films. However, higher peaks from CZTS-3cycles and CZTS-5cycles cannot be achieved only by absorbed hydrogen from H 2 O, so it is highly likely that most of the hydrogen detected already resides in the CZTS layer.…”

Section: In This Research a New Route Of Surface Passivation Is Repomentioning

confidence: 99%

“…[8a] It is known that, in ALD process, the precursor molecule and the reactant which are trimethylaluminum (TMA, Al(CH 4 ) 3 ) and H 2 O respectively, [9,10] are the hydrogen sources needed for chemical passivation. [14] However, the detailed passivation route is unknown. [12] For field effect passivation, it has been reported that a critical thickness is required to ensure this field effect.…”

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The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

Park

Huang

Yun

et al. 2018

Advanced Energy Materials

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record 9.5% efficiency pure sulfide CZTS solar cell, [4] but it is still much lower than the S-Q limit and its CuInGaSe 2 (CIGS) counterpart. It has been identified that the main reason for the efficiency limitation is the open-circuit voltage (V oc ) deficit (E g /q −V oc , where q is the elemental charge) as a result of band fluctuation and nonradiative recombination. [5] In addition, unfavorable conduction band alignment, i.e., cliff-like conduction band offset, at the interface of CZTS absorber/ CdS has been reported to lead to high recombination, contributing to the loss of V oc . [6] The majority of electron-hole pairs are generated near the CZTS/CdS interface, [7] so the passivation of the CZTS/ CdS interface is of crucial importance in achieving high-performance CZTS solar cells. In CIGS solar cells, Al 2 O 3 was employed for better surface passivation. [8] In these papers, both field effect passivation by fixed negative charge and chemical passivation play a role in passivating the CIGS surface, and decrease surface recombination velocity. The thickness of Al 2 O 3 used in these studies is few tens of nanometers which are not suitable for the heterojunction passivation as such a thick layer would impede carrier flow at the junction area.We employed an ultrathin atomic layer deposited (ALD)-Al 2 O 3 layer, which is believed to effectively reduce interfacial recombination by reacting with the surface defects. [8a] It is known that, in ALD process, the precursor molecule and the reactant which are trimethylaluminum (TMA, Al(CH 4 ) 3 ) and H 2 O respectively, [9,10] are the hydrogen sources needed for chemical passivation. The passivation mechanism of ALD-Al 2 O 3 in the silicon solar cells can be divided into two categories: i) field effect passivation induced by negative fixed charges [11] and ii) chemical passivation by hydrogen. [12] For field effect passivation, it has been reported that a critical thickness is required to ensure this field effect. [13] Based on the benefits of ALD-Al 2 O 3 , the kesterite group at IBM has recently reported the passivation of CZTSSe/CdS interface by a thin ALD-Al 2 O 3 layer (less than 1 nm) showing enhanced performance due to surface passivation effects. [14] However, the detailed passivation route is unknown. The effect of ultrathin (less than 1 nm) Al 2 O 3 on interface passivation is unclear as negative fixed charges may not be involved in the passivation effect.

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Atomic Layer Deposited Aluminum Oxide for Interface Passivation of Cu₂ZnSn(S,Se)₄ Thin‐Film Solar Cells

Cited by 90 publications

References 29 publications

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation

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Atomic Layer Deposited Aluminum Oxide for Interface Passivation of Cu2ZnSn(S,Se)4 Thin‐Film Solar Cells

Cited by 90 publications

References 29 publications

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO2 at Absorber/HTL Interface

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO2 at Absorber/HTL Interface

Passivation of Interfaces in Thin Film Solar Cells: Understanding the Effects of a Nanostructured Rear Point Contact Layer

The Role of Hydrogen from ALD‐Al2O3 in Kesterite Cu2ZnSnS4 Solar Cells: Grain Surface Passivation

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Product

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Atomic Layer Deposited Aluminum Oxide for Interface Passivation of Cu₂ZnSn(S,Se)₄ Thin‐Film Solar Cells

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO₂ at Absorber/HTL Interface

The Role of Hydrogen from ALD‐Al₂O₃ in Kesterite Cu₂ZnSnS₄ Solar Cells: Grain Surface Passivation