Back-Contacted Silicon Heterojunction Solar Cells: Optical-Loss Analysis and Mitigation

Paviet‐Salomon, Bertrand; Tomasi, A.; Descoeudres, Antoine; Barraud, Loris; Nicolay, Sylvain; Despeisse, M.; Wolf, Stefaan De; Ballif, Christophe

doi:10.1109/jphotov.2015.2438641

Cited by 46 publications

(35 citation statements)

References 56 publications

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“…We estimate the high series resistance contribution to originate from the (p)a-Si:H/ITO contact, as we reported before for both side contacted cells using the same processes [25]. The high pFFs also show that the precisely aligned p-and ndoped areas indeed do not cause a shunt, thanks to their low conductivity [26].…”

Section: B Solar Cellssupporting

confidence: 69%

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

Ring

Kirner

Schultz

et al. 2016

IEEE J. Photovoltaics

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A novel emitter patterning method for backcontacted Si heterojunction solar cells is presented, which combines laser processing and wet etching of a mask layer stack with self-aligned repassivation, thus reducing the process complexity, as compared with the commonly used emitter patterning methods. Lifetime samples demonstrate that with a suitable mask stack, laser scribing can be performed without inducing laser damage to the passivation. Despite nonoptimal wet etch and repassivation processes which currently limit the obtained lifetime, proof-of-concept cells on p-type wafers fabricated using this novel emitter patterning process and lithographically patterned metallization exhibit an open-circuit voltage of 694 mV and pseudo-fill-factors of 83%. With the laser written mask layers for etching and self-aligned passivation process, we have thus developed the proof-of-concept for a simple, lithography free, and contactless emitter patterning method for industrial applicationsIndex Terms-Heterojunction silicon solar cells, interdigitated back-contact (IBC), laser processing, self-alignment.

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Section: B Solar Cellssupporting

confidence: 69%

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

Ring

Kirner

Schultz

et al. 2016

IEEE J. Photovoltaics

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“…The possibility of such high injection efficiencies provides an opportunity for an improved collection efficiency for a‐Si–passivated solar cells. This might also explain the experimentally observed current losses in IBC cells that are lower than expected from optical simulations …”

Section: Resultsmentioning

confidence: 99%

Measuring carrier injection from amorphous silicon into crystalline silicon using photoluminescence

Paduthol

Juhl

Nogay

et al. 2018

Progress in Photovoltaics

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In devices with intrinsic amorphous silicon layer on a crystalline silicon substrate, the light absorbed in the amorphous layer can be weakly electronically coupled into the silicon base. Such carrier injection has previously been reported from measurements on finished devices containing stacks of intrinsic and doped amorphous silicon layers. Here, we use spectral response of photoluminescence, a contactless approach, to investigate this carrier injection on significantly simpler structures. In such devices, the effect of absorption in the front layer can be measured by the internal quantum efficiency. A highly absorbing front layer is expected to cause a drop in the quantum efficiency at short wavelengths. However, if electron‐hole pairs that are generated in the front layer are subsequently injected into the base, the optical losses will be reduced, resulting in a partial recovery of the quantum efficiency at short wavelengths. Here, we quantify the efficiency of carrier injection from the intrinsic amorphous silicon front layer to the crystalline silicon base, by measuring the spectral response of photoluminescence heterojunction test structures. For devices with just an intrinsic amorphous silicon layer, the carrier injection from the layer was found to be close to unity.

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“…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 industry over the past decade [14][15][16][17][18][19][20][21] , resulting in the past few years in several record devices with efficiencies ≥25% (refs 22-26). Technologically, it is of note that all these outstanding results have been reached with passivating contacts that are either silicon-oxide-based 22 or fabricated by low-temperature depositions of hydrogenated silicon thin films [24][25][26] , distinctive of the so-called silicon heterojunction (SHJ) technology (ref.…”

mentioning

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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Back-Contacted Silicon Heterojunction Solar Cells: Optical-Loss Analysis and Mitigation

Cited by 46 publications

References 56 publications

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

Emitter Patterning for Back-Contacted Si Heterojunction Solar Cells Using Laser Written Mask Layers for Etching and Self-Aligned Passivation (LEAP)

Measuring carrier injection from amorphous silicon into crystalline silicon using photoluminescence

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

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