Novel Approach for the Bonding of III-V on Silicon Tandem Solar Cells with a Transparent Conductive Adhesive

Heitmann, Ulrike; Kluska, Sven; Bartsch, Jonas; Hauser, Hubert; Ivanov, Alexey; Janz, S.

doi:10.1109/pvsc.2018.8548276

Cited by 5 publications

(7 citation statements)

References 11 publications

(11 reference statements)

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“…Losses due to parasitic absorption in the ZnO-based TCA layer are below 2% within the relevant wavelength range, as it has been already demonstrated [7]. Also, very promising results for a TiO 2 -based ARC at the TCA-semiconductor interface have already been published [1].…”

Section: Optical Simulation Of Bond Layermentioning

confidence: 59%

Pathways and Potentials for III–V on Si Tandem Solar Cells Realized Using a ZnO-Based Transparent Conductive Adhesive

Heitmann

Bartsch

Kluska

et al. 2021

IEEE J. Photovoltaics

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This work presents a new type of transparent conductive adhesive and its electrical and optical properties with regards to an application in III-V on Silicon tandem solar cells. The developed adhesive is based on a doped ZnO and deposited by spray coating. The optical interconnection of the two sub-cells is identified as one of the major challenges due to the reflectance at the bond and possible approaches to reduce the reflectance are investigated by optical simulations. Regarding the electrical interconnection, an ITO-based contact layer reduced the lowest measured connecting resistivity from previously 17 Ω•cm² [1] down to 0.12 Ω•cm². It is shown that the homogeneity of the bond correlates with its conductivity and can be improved by adjusting the glueing process according to the calcination process of the adhesive. Taking both the electrical and optical parameters of the transparent conductive adhesive into account, the efficiency of a triple junction solar cell was estimated.

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Section: Optical Simulation Of Bond Layermentioning

confidence: 59%

Pathways and Potentials for III–V on Si Tandem Solar Cells Realized Using a ZnO-Based Transparent Conductive Adhesive

Heitmann

Bartsch

Kluska

et al. 2021

IEEE J. Photovoltaics

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“…A simplified sketch of the glued cell structure is shown in Figure 2. However, the developed bonding process flow as described in [4] did not result in mechanically stable bonds. Only by implementing an initial pressing at a low temperature (125°C, 0.33 N/cm²), a mechanically stable interconnection of a III-V/Si tandem solar cell (both semiconductor surfaces at the bond planar) was realized.…”

Section: Bonding Of the First Tandem Solar Cellmentioning

confidence: 98%

“…Implementing a particle-based TCA (Ag coated particles) has already shown a very promising efficiency of 26.4% (in two-terminal configuration) [3]. In this publication we will show the progress of a newly developed particle-free TCA, which does not need the addition of conductive particles but becomes conductive itself upon thermal annealing at 300°C [4]. The adhesive is a dissolved zinc precursor which upon heating decomposes to ZnO.…”

Section: Introductionmentioning

confidence: 98%

“…The adhesive is a dissolved zinc precursor which upon heating decomposes to ZnO. This developed TCA already demonstrated good optical properties (absorption below 2% for an 1-2µm thick layer for wavelengths between 600 and 1200 nm) and a low connecting resistivity (1 Ωcm 2 ) in glassglass and Si-Si test structures, respectively [4]. It was also found, that the reflectance at the TCA bond layer significantly affects the performance of the tandem device [5].…”

Section: Introductionmentioning

confidence: 99%

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The First Glued Tandem Solar Cell Using a ZnO Based Adhesive

Heitmann

Bartsch

Kluska

et al. 2020

2020 47th IEEE Photovoltaic Specialists Conference (PVSC)

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By adjusting the process flow of a newly developed transparent conductive adhesive (TCA), the first mechanically stable interconnection of a glued III-V on Si tandem solar cell was established utilizing a ZnO-based adhesive. The measured VOC of 1691 mV is a first proof of concept for the developed TCA. The functionality of the two sub-cells in the tandem device was proven by external quantum efficiency (EQE) measurements. The reflectance at the bond interface of such a glued tandem solar cell remains the limiting factor. In order to reduce the optical losses, the effect of a textured silicon surface was investigated in test structures, which indeed showed reduced reflectance. Furthermore, this textured test structure showed an improved connecting resistivity as low as 83 mΩcm².

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“…The concept of HBTSC is material-agnostic, but in this paper, we will focus on the case where the HBTSC is made of III-V semiconductors. For the III-V-HBTSC-on-Si device to be cost-effective, the III-V HBTSC has to be fabricated with lowcost techniques, transferred to the top of the silicon cell and glued with a low-cost transparent conductive adhesive [4], [5]. If other materials are chosen, potentially cheaper fabrication techniques could be employed, possibly at the cost of efficiency.…”

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confidence: 99%

III-V-on-silicon triple-junction based on the heterojunction bipolar transistor solar cell concept

Antolín

Zehender

Svatek

et al. 2020

2020 47th IEEE Photovoltaic Specialists Conference (PVSC)

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We propose a new triple-junction solar cell structure composed of a III-V heterojunction bipolar transistor solar cell (HBTSC) stacked on top of, and series-connected to, a Si solar cell (III-V-HBTSC-on-Si). The HBTSC is a novel threeterminal device, whose viability has been recently experimentally demonstrated. It has the theoretical efficiency limit of an independently-connected double-junction solar cell. Here, we perform detailed balance efficiency limit calculations under onesun illumination that show that the absolute efficiency limit of a III-V-HBTSC-on-Si device is the same as for the conventional current-matched III-V-on-Si triple-junction (47% assuming black-body spectrum, 49% with AM1.5G). However, the range of band-gap energies for which the efficiency limit is above 40% is much wider in the III-V-HBTSC-on-Si stack case. From a technological point of view, the lattice-matched GaInP/GaAs combination is particularly interesting, which has an AM1.5G efficiency limit of 47% with the HBTSC-on-Si structure and 39% if the current-matched III-V-on-Si triple junction is considered. Moreover, we show that interconnecting the terminals of the HBTSC to achieve a two-terminal GaInP/GaAs-HBTSC-on-Si device only reduces the efficiency limit by three points, to 43%. As a result, the GaInP/GaAs-HBTSC-on-Si solar cell becomes a promising device for two-terminal, high-efficiency one-sun operation. For it to also be cost-effective, low-cost technologies must be applied to the III-V material growth, such as highthroughput epitaxy or sequential growth.

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Novel Approach for the Bonding of III-V on Silicon Tandem Solar Cells with a Transparent Conductive Adhesive

Cited by 5 publications

References 11 publications

Pathways and Potentials for III–V on Si Tandem Solar Cells Realized Using a ZnO-Based Transparent Conductive Adhesive

Pathways and Potentials for III–V on Si Tandem Solar Cells Realized Using a ZnO-Based Transparent Conductive Adhesive

The First Glued Tandem Solar Cell Using a ZnO Based Adhesive

III-V-on-silicon triple-junction based on the heterojunction bipolar transistor solar cell concept

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