Transparent Electrodes in Silicon Heterojunction Solar Cells: Influence on Contact Passivation

Tomasi, A.; Sahli, Florent; Seif, Johannes P.; Fanni, Lorenzo; Agut, Silvia Martin de Nicolas; Geissbühler, Jonas; Paviet‐Salomon, Bertrand; Nicolay, Sylvain; Barraud, Loris; Niesen, Bjoern; Wolf, Stefaan De; Ballif, Christophe

doi:10.1109/jphotov.2015.2484962

Cited by 41 publications

(26 citation statements)

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“…266 While such transparent conductive oxides clearly lead to an increase in the current density, the use of hydrogenated amorphous silicon oxide or silicon carbide often results in a reduced fill factor, and neutralizes the gains in short-circuit current. In general, fill factor losses related to transparent conductive oxides are due to a suboptimally matched work function, 267,268 or to increased sheet or contact resistances between the transparent conductive oxide and the doped amorphous silicon layers. 269 Transparent conductive oxides typically exhibit n-type conductivity and consequently readily form an Ohmic contact to n-type hydrogenated amorphous silicon.…”

Section: Reviewmentioning

confidence: 99%

High-efficiency crystalline silicon solar cells: status and perspectives

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Cuevas

Wolf

2016

Energy Environ. Sci.

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Section: Reviewmentioning

confidence: 99%

High-efficiency crystalline silicon solar cells: status and perspectives

Battaglia

Cuevas

Wolf

2016

Energy Environ. Sci.

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873

575

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“…Consequently, the low doping efficiency of boron in a-Si:H can lead to inadequate band bending at the c-Si surface, and so FF issues attributed to injection-dependent recombination at the hole contact. 78,79 The most commonly ascribed shortcoming of the SHJ approach in terms of its ultimate performance is the parasitic absorption occurring in the front a-Si:H layers and TCO (typically ITO) that provides lateral charge transport. 80 Recent PCE improvements have consequently come from implementing the more complex IBC design, which places both contacts on the rear side of the cell, removing both the TCO and doped a-Si:H from the sun-facing side of the device.…”

Section: Mis Passivating Contactsmentioning

confidence: 99%

Passivating contacts for crystalline silicon solar cells

et al. 2019

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The global photovoltaic (PV) market is dominated by crystalline silicon (c-Si) based technologies with heavily doped, directly metallised contacts. Recombination of photogenerated electrons and holes at the contact regions is increasingly constraining the power conversion efficiencies of these devices as other performance-limiting energy losses are overcome. To move forward, c-Si PV technologies must implement alternative contacting approaches. Passivating contacts, which incorporate thin films within the contact structure that simultaneously supress recombination and promote charge carrier selectivity, are a promising next step for the mainstream c-Si PV industry. In this work we review the fundamental physical processes governing contact formation in c-Si. In doing so we identify the role passivating contacts play in increasing c-Si solar cell efficiencies beyond the limitations imposed by heavy doping and direct metallisation. Strategies towards the implementation of passivating contacts in industrial environments are discussed.

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“…For a stack of sufficiently thin layers, the resulting c-Si surface potential can be affected by the presence of overlying films that are not directly in contact with the c-Si surface. Even the uppermost film in thin three-layer stacks, such as the TCO film in SHJ contacts, may influence the underlying c-Si surface potential 49,50 . Consequently, to guarantee high electron selectivity, the Si:H(n) layer of the interband-tunnelling contact must be engineered to induce, but also to shield the c-Si surface potential from the presence of the Si:H(p) overlayer.…”

Section: Requirements For E Cient Tunnel-ibc Solar Cellsmentioning

confidence: 99%

Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

et al. 2017

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For crystalline-silicon solar cells, voltages close to the theoretical limit are nowadays readily achievable when using passivating contacts. Conversely, maximal current generation requires the integration of the electron and hole contacts at the back of the solar cell to liberate its front from any shadowing loss. Recently, the world-record e ciency for crystalline-silicon singlejunction solar cells was achieved by merging these two approaches in a single device; however, the complexity of fabricating this class of devices raises concerns about their commercial potential. Here we show a contacting method that substantially simplifies the architecture and fabrication of back-contacted silicon solar cells. We exploit the surface-dependent growth of silicon thin films, deposited by plasma processes, to eliminate the patterning of one of the doped carrier-collecting layers. Then, using only one alignment step for electrode definition, we fabricate a proof-of-concept 9-cm 2 tunnel-interdigitated backcontact solar cell with a certified conversion e ciency >22.5%. I n recent decades, the market of photovoltaics has been consistently growing and the yearly installed photovoltaic capacity has increased from 328 MW peak in 2001 to 50 GW peak in 2015. This resulted in 2016 in a cumulative capacity of 235 GW peak (ref. 1), largely based on crystalline-silicon (c-Si) solar-cell technologies 2 , and contributing to about 1.3% of the global electricity production 3 . To further increase this number, the cost-competitiveness of photovoltaics must surpass that of classic, non-renewable energy sources, and one route towards this goal is to raise the conversion efficiency of industrial c-Si solar cells 4,5 .High power conversion efficiencies require maximizing the solar-cell electrical parameters: open-circuit voltage (V oc ), fillfactor (FF) and short-circuit current density (J sc ). For the V oc and FF, this is possible by using passivating contacts, employing silicon oxide or hydrogenated amorphous silicon (a-Si:H) thin films to minimize charge carrier recombination at the electrical contacts to the c-Si wafer, with demonstrated record efficiencies for two-sidecontacted solar cells of 25.1% (refs 6,7). Maximum J sc values can be achieved using a back-contacted architecture, eliminating front metal electrode shadowing and minimizing optical reflection and absorption losses at the front. Small-sized back-contacted solar cells, based on diffused silicon homo-junctions, were realized at several research institutes (refs 8-11), showing a best conversion efficiency up to 24.4% (ref. 12). Industrially, the back-contacted architecture was pioneered by Sunpower, recently reporting on large-area devices with very high J sc values and efficiencies surpassing 25% (ref. 13). Considering these achievements, integrating passivating contacts in a back-contacted architecture is the obvious c-Si single-junction solar-cell design towards highest conversion efficiencies. Such an approach has increasingly been researched in both academia and indust...

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Transparent Electrodes in Silicon Heterojunction Solar Cells: Influence on Contact Passivation

Cited by 41 publications

References 50 publications

High-efficiency crystalline silicon solar cells: status and perspectives

High-efficiency crystalline silicon solar cells: status and perspectives

Passivating contacts for crystalline silicon solar cells

Simple processing of back-contacted silicon heterojunction solar cells using selective-area crystalline growth

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