Light-induced performance increase of silicon heterojunction solar cells

Kobayashi, Eiji; Wolf, Stefaan De; Levrat, Jacques; Christmann, Gabriel; Descoeudres, Antoine; Nicolay, Sylvain; Despeisse, M.; Watabe, Y.; Ballif, Christophe

doi:10.1063/1.4964835

Cited by 73 publications

(67 citation statements)

References 45 publications

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“…4b. Light-soaking improved the conversion efficiency by about 0.3% absolute, in agreement with the recent findings of Kobayashi and colleagues 31 . With this measurement, we demonstrated a maximum conversion efficiency of 22.9% for the tunnel-IBC solar cell.…”

Section: High-e Ciency Proof-of-concept Tunnel-ibc Solar Cellssupporting

confidence: 92%

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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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Section: High-e Ciency Proof-of-concept Tunnel-ibc Solar Cellssupporting

confidence: 92%

“…Our best tunnel-IBC solar cell, realized with a single alignment step and no photolithographic patterning, has a conversion efficiency >22.5%, which improves slightly after light-soaking 31 .…”

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confidence: 96%

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

et al. 2017

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“…Furthermore, a‐Si:H cells are well known to undergo LID through the Staebler‐Wronski effect. Notably, whereas it has been shown that LID can cause some degradation of intrinsic a‐Si/c‐Si interface passivation structures, it was recently found that, on the device level, SHJ cells actually improve their efficiency under light exposure …”

Section: Discussion and Outlookmentioning

confidence: 99%

“…This is most likely due to dopant‐induced defect generation in a‐Si:H layers . Remarkbly, such stacked films, featuring a doped layer, lead to improved passivation upon extended light soaking, resulting in improved efficiencies of finalized devices …”

Section: Status Of High Efficiency Shj Cellsmentioning

confidence: 99%

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Chavali

Wolf

Alam

2018

Progress in Photovoltaics

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The device physics of commercially dominant diffused-junction silicon solar cells is well understood, allowing sophisticated optimization of this class of devices. Recently, so-called passivating-contact solar cell technologies have become prominent, with Kaneka setting the world's silicon solar cell efficiency record of 26.63% using silicon heterojunction contacts in an interdigitated configuration. Although passivating-contact solar cells are remarkably efficient, their underlying device physics is not yet completely understood, not in the least because they are constructed from diverse materials that may introduce electronic barriers in the current flow.To bridge this gap in understanding, we explore the device physics of passivating contact silicon heterojunction (SHJ) solar cells. Here, we identify the key properties of heterojunctions that affect cell efficiency, analyze the dependence of key heterojunction properties on carrier transport under light and dark conditions, provide a self-consistent multiprobe approach to extract heterojunction parameters using several characterization techniques (including dark J-V, light J-V, C-V, admittance spectroscopy, and Suns-Voc), propose design guidelines to address bottlenecks in energy production in SHJ cells, and develop a process-to-module modeling framework to establish the module's performance limits. We expect that our proposed guidelines resulting from this multiscale and self-consistent framework will improve the performance of future SHJ cells as well as other passivating contact-based solar cells.

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“…The development of surface passivation and interface control schemes is essential for the development of semiconductor technologies, such as Si solar cells and high electron mobility transistors (HEMTs) . Passivation strategies for high‐vacuum and/or high‐temperature techniques, such as Al 2 O 3 , SiO 2 , and hydrogenated amorphous silicon (a‐Si:H), have garnered significant attention due to their excellent passivation effects .…”

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confidence: 99%

Improving the Passivation Stability of a Polymer Thin Film on Si by the Introduction of MoO₃ Nanoparticles Into the Polymer Matrix

Chen

et al. 2017

Phys. Status Solidi RRL

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MoO3 nanoparticles with high work functions were introduced into a polystyrene sulfonic acid (PSS) thin‐film matrix to form PSS:MoO3 (PSSMO) composite thin films, improving the stability of the PSS passivation effect spoiled by the self‐deoxidation at the PSS/Si interface based on an electrical passivation mechanism, which was found in previous work. Compared to the PSS/Si interface, the direction of the internal electric field (Ein) was reversed through the PSSMO/Si interface, which changed the Ein‐induced deoxidation at the PSS/Si interface to Ein‐induced oxidation at the PSSMO/Si interface, corresponding to a light‐induced enhancement of the PSSMO passivation rather than a light‐induced degradation of PSS passivation. In addition, it was shown that PSSMO has good electrical and optical properties. Thus, a versatile thin film with the properties of surface passivation, hole transport and high transmission was obtained.

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Light-induced performance increase of silicon heterojunction solar cells

Cited by 73 publications

References 45 publications

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

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

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Improving the Passivation Stability of a Polymer Thin Film on Si by the Introduction of MoO₃ Nanoparticles Into the Polymer Matrix

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Light-induced performance increase of silicon heterojunction solar cells

Cited by 73 publications

References 45 publications

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

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

Device physics underlying silicon heterojunction and passivating‐contact solar cells: A topical review

Improving the Passivation Stability of a Polymer Thin Film on Si by the Introduction of MoO3 Nanoparticles Into the Polymer Matrix

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Improving the Passivation Stability of a Polymer Thin Film on Si by the Introduction of MoO₃ Nanoparticles Into the Polymer Matrix