Tantalum Nitride Electron‐Selective Contact for Crystalline Silicon Solar Cells

Yang, Xinbo; Aydın, Erkan; Xu, Hang; Kang, Jingxuan; Hedhili, Mohamed N.; Liu, Wenzhu; Wan, Yimao; Peng, Jun; Samundsett, Christian; Cuevas, Andrés; Wolf, Stefaan De

doi:10.1002/aenm.201800608

Cited by 133 publications

(145 citation statements)

References 47 publications

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“…This relatively low ρ c is comparable to the high quality CSCs such as n + poly‐Si/SiO 2 /c‐Si by Yan et al and TiO x /SiO x /c‐Si by Yang et al, which led to PCE of more than 20%. A relatively low ρ c value for sample‐(E) would be attributed to a lowering of work function by a reduction of TiO x and/or Fermi‐level depinning caused by a high level of passivation performance …”

Section: Influence Of the Siox Interlayers Prepared By Different Chemmentioning

confidence: 99%

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Mochizuki

Gotoh

Kurokawa

et al. 2018

Adv Materials Inter

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Section: Influence Of the Siox Interlayers Prepared By Different Chemmentioning

confidence: 99%

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Mochizuki

Gotoh

Kurokawa

et al. 2018

Adv Materials Inter

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“…[1][2][3][4][5][6][7] Such an approach has potential benefits over conventional heavily doped direct-metallization approaches, including lower processing temperatures, simpler contact formation, and the removal of fundamental limitations, such as Auger recombination and free carrier absorption. For example, materials such as metal oxides, nitrides, and fluorides have been demonstrated to form electron and hole selective interfaces when applied to c-Si.…”

mentioning

confidence: 99%

Dopant‐Free Partial Rear Contacts Enabling 23% Silicon Solar Cells

Bullock

Wan

Hettick

et al. 2019

Advanced Energy Materials

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improving the performance of this technology. For example, materials such as metal oxides, nitrides, and fluorides have been demonstrated to form electron and hole selective interfaces when applied to c-Si. [1][2][3][4][5][6][7] Such an approach has potential benefits over conventional heavily doped direct-metallization approaches, including lower processing temperatures, simpler contact formation, and the removal of fundamental limitations, such as Auger recombination and free carrier absorption. [8,9] In addition, the unique interface properties of some metal compound/c-Si interfaces have even enabled novel solar cell architectures, for example, n-type c-Si cells with undoped partial rear contacts (PRCs). [10,11] This specific architecture utilizes a near-ideal surface passivation layer, such as hydrogenated silicon nitride SiN x , [12] to cover the vast majority of the rear surface which can greatly reduce the average surface recombination factor J 0 and increase the rear reflection. Only a small percentage of the area is contacted, typically < 5%, where electrons flow to be collected. An n-type undoped PRC cell structure was not previously attainable due to the tendency of n-type c-Si to form an interface potential barrier under direct metallization, which resulted in prohibitively high contact resistivity ρ c . The first successful demonstration of this cell came after a breakthrough in low resistance interfaces to n-type c-Si with a low work function LiF x /Al electrode. This contact was used to fabricate an undoped PRC cell attaining an efficiency of 20.6% with a PRC covering only ≈1% of the rear surface. [11] The next evolutionary step in this cell structure was the integration of a passivation layer at the PRC interface. This came with the introduction of a TiO x /Ca/Al contact, [10] which was found to provide both reduced surface recombination and low contact resistivity, enabling an efficiency of 21.8%. Following on from these early developments, there exist three major avenues to easily improve the electron PRC: i) reduction in the PRC interface recombination and resistivity; ii) increase in the PRC material's stability to thermal stressors; and iii) increasing the rear surface reflectivity via appropriate choice of PRC materials.This article introduces the next in this family of carrier selective interfaces, which targets the abovementioned three issues. To address this a TiO x /LiF x /Al heterocontact is developed and integrated into a PRC cell shown in Figure 1a. The

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“…These drawbacks have stimulated the development of devices featuring alternative carrier‐selective materials such as metal oxides, nitrides, fluorides, and organic materials . Functional contact stacks relying on such electron and hole transport layers (ETLs and HTLs, respectively) are therefore often referred to as “dopant‐free” contacts, although the real attractive feature is that these contacts are free of any heavily doped Si region (internal or external to the wafer), resulting in a high optical transparency.…”

Section: Introductionmentioning

confidence: 99%

Mitigating Plasmonic Absorption Losses at Rear Electrodes in High‐Efficiency Silicon Solar Cells Using Dopant‐Free Contact Stacks

Zhong

Dréon

Jeangros

et al. 2019

Adv Funct Materials

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Although charge-carrier selectivity in conventional crystalline silicon (c-Si) solar cells is usually realized by doping Si, the presence of dopants imposes inherent performance limitations due to parasitic absorption and carrier recombination. The development of alternative carrier-selective contacts, using non-Si electron and hole transport layers, has the potential to overcome such drawbacks and simultaneously reduce the cost and/or simplify the fabrication process of c-Si solar cells. Nevertheless, devices relying on such non-Si contacts with power conversion efficiencies (PCEs) that rival their classical counterparts are yet to be demonstrated. In this study, one key element is brought forward toward this demonstration by incorporating low-pressure chemical vapor deposited ZnO as the electron transport layer in c-Si solar cells. Placed at the rear of the device, it is found that rather thick (75 nm) ZnO film capped with LiF x /Al simultaneously enables efficient electron selectivity and suppression of parasitic infrared absorption. Next, these electron-selective contacts are integrated in c-Si solar cells with MoO x -based hole-collecting contacts at the device front to realize full-area dopant-freecontact solar cells. In the proof-of-concept device, a PCE as high as 21.4% is demonstrated, which is a record for this novel device class and is at the level of conventional industrial solar cells.

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Tantalum Nitride Electron‐Selective Contact for Crystalline Silicon Solar Cells

Cited by 133 publications

References 47 publications

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Dopant‐Free Partial Rear Contacts Enabling 23% Silicon Solar Cells

Mitigating Plasmonic Absorption Losses at Rear Electrodes in High‐Efficiency Silicon Solar Cells Using Dopant‐Free Contact Stacks

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Tantalum Nitride Electron‐Selective Contact for Crystalline Silicon Solar Cells

Cited by 133 publications

References 47 publications

Local Structure of High Performance TiOx Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiOx Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Dopant‐Free Partial Rear Contacts Enabling 23% Silicon Solar Cells

Mitigating Plasmonic Absorption Losses at Rear Electrodes in High‐Efficiency Silicon Solar Cells Using Dopant‐Free Contact Stacks

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Product

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Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy

Local Structure of High Performance TiO_x Electron‐Selective Contact Revealed by Electron Energy Loss Spectroscopy