Multiscale Transparent Electrode Architecture for Efficient Light Management and Carrier Collection in Solar Cells

Boccard, Mathieu; Battaglia, Corsin; Hänni, Simon; Söderström, Karin; Escarré, Jordi; Nicolay, Sylvain; Meillaud, Fanny; Despeisse, M.; Ballif, Christophe

doi:10.1021/nl203909u

Cited by 126 publications

(86 citation statements)

References 42 publications

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“…Furthermore, the contact layer needs to be textured particularly with regard to the application in thin-film silicon solar cells. 8,11,12 The textured surface induces an elongated light path within the thin absorber layer that facilitates absorption. As a result, short-circuit current density and thus the solar cell's conversion efficiency increase.…”

Section: Introductionmentioning

confidence: 99%

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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This work elucidates the effect of the dopant aluminum on the growth of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films by means of a seed layer concept. Thin (<100 nm), highly doped seed layers and subsequently grown thick (∼800 nm), lowly doped bulk films were deposited using a ZnO:Al2O3 target with 2 wt. % and 1 wt. % Al2O3, respectively. We investigated the effect of bulk and seed layer deposition temperature as well as seed layer thickness on electrical, optical, and structural properties of ZnO:Al films. A reduction of deposition temperature by 100 °C was achieved without deteriorating conductivity, transparency, and etching morphology which renders these low-temperature films applicable as light-scattering front contact for thin-film silicon solar cells. Lowly doped bulk layers on highly doped seed layers showed smaller grains and lower surface roughness than their counterpart without seed layer. We attributed this observation to the beneficial role of the dopant aluminum that induces an enhanced surface diffusion length via a surfactant effect. The enhanced surface diffusion length promotes 2D-growth of the highly doped seed layer, which is then adopted by the subsequently grown and lowly doped bulk layer. Furthermore, we explained the seed layer induced increase of tensile stress on the basis of the grain boundary relaxation model. The model relates the grain size reduction to the tensile stress increase within the ZnO:Al films. Finally, temperature-dependent conductivity measurements, optical fits, and etching characteristics revealed that seed layers reduced grain boundary scattering. Thus, seed layers induced optimized grain boundary morphology with the result of a higher charge carrier mobility and more suitable etching characteristics. It is particularly compelling that we observed smaller grains to correlate with an enhanced charge carrier mobility. A seed layer thickness of 5 nm was sufficient to induce the beneficial effects.

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Section: Introductionmentioning

confidence: 99%

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Sommer

Stanley

Köhler

et al. 2015

Journal of Applied Physics

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“…The micromorph technology, which combines amorphous (a-Si:H) and microcrystalline (mc-Si:H) silicon for the top and bottom cells, respectively, is in that regard a promising approach. Indeed this architecture has recently demonstrated laboratory cell efficiencies above 14% [1,2] and 12.3% [3,4] in the initial and stabilized states, respectively. At the same time, many groups have successfully developed various plasma-enhanced chemical vapor deposition (PE-CVD) processes to fabricate high-quality mc-Si:H bottom cells at high deposition rates above 1 nm/s [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

New progress in the fabrication of n–i–p micromorph solar cells for opaque substrates

Biron

Hänni

Boccard

et al. 2013

Solar Energy Materials and Solar Cells

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a b s t r a c tIn this paper, we investigate tandem amorphous/microcrystalline silicon solar cells with asymmetric intermediate reflectors grown in the n-i-p substrate configuration. We compare different types of substrates with respect to their light-trapping properties as well as their influence on the growth of single-junction microcrystalline cells. Our most promising back reflector combines a textured zinc oxide film grown by low-pressure chemical vapor deposition, a silver film for reflection, and a zinc oxide buffer layer. Grown on this substrate, microcrystalline cells exhibit excellent response in the infrared while keeping high open-circuit voltage and fill factor, leading to efficiencies of up to 10.0%. After optimizing the morphology of the asymmetric intermediate reflector, we achieve an n-i-p micromorph solar cell stabilized efficiency of 11.6%, using 270 nm and 1.7 mm of silicon for the absorber layer of the amorphous top cell and the microcrystalline bottom cell, respectively. Using this original device architecture, we reach efficiencies close to those of state-of-the-art n-i-p and p-i-n micromorph devices, demonstrating a promising route to deposit high-efficiency thin-film silicon solar cells on opaque substrates.

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“…Effective light trapping in thin-film microcrystalline silicon (lc-Si:H) solar cells is crucial to obtain high photocurrent and to reduce the absorber layer thickness, which in state-of-the-art devices is commonly realized using randomly textured substrates. [1][2][3][4][5] Recently, plasmonic metal nanoparticles have attracted extensive interest to further improve the light trapping in solar cells since metal nanoparticles can efficiently scatter the incident light into absorber layer. [6][7][8][9][10][11][12][13][14] Enhanced photocurrent in lc-Si:H solar cells has been demonstrated using periodic metallic gratings and random metal nanoparticles as rear reflectors, which here we refer to as plasmonic back reflector (BR).…”

mentioning

confidence: 99%

Improved light trapping in microcrystalline silicon solar cells by plasmonic back reflector with broad angular scattering and low parasitic absorption

Hui‐min

Sivec²,

Yan³

et al. 2013

Applied Physics Letters

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We show experimentally that the photocurrent of thin-film hydrogenated microcrystalline silicon (lc-Si:H) solar cells can be enhanced by 4.5 mA/cm 2 with a plasmonic back reflector (BR). The light trapping performance is improved using plasmonic BR with broader angular scattering and lower parasitic absorption loss through tuning the size of silver nanoparticles. The lc-Si:H solar cells deposited on the improved plasmonic BR demonstrate a high photocurrent of 26.3 mA/cm 2 which is comparable to the state-of-the-art textured Ag/ZnO BR. The commonly observed deterioration of fill factor is avoided by using lc-SiO x :H as the n-layer for solar cells deposited on plasmonic BR. V C 2013 AIP Publishing LLC [http://dx

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Multiscale Transparent Electrode Architecture for Efficient Light Management and Carrier Collection in Solar Cells

Cited by 126 publications

References 42 publications

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

Role of the dopant aluminum for the growth of sputtered ZnO:Al investigated by means of a seed layer concept

New progress in the fabrication of n–i–p micromorph solar cells for opaque substrates

Improved light trapping in microcrystalline silicon solar cells by plasmonic back reflector with broad angular scattering and low parasitic absorption

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