Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

Bennett, Mitchell F.; Bittner, Zachary S.; Forbes, David V.; Tatavarti, Sudersena Rao; Ahrenkiel, S. Phillip; Wibowo, Andree; Pan, N.; Kevin, Chern,; Hubbard, Seth M.

doi:10.1063/1.4833776

Cited by 16 publications

(9 citation statements)

References 20 publications

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“…Moreover, photon trapping and recycling enabled by the thin-film design have been proven to be essential to push the efficiency of III-V single-junction cells towards the SQ limit [31,32,33], and are in fact at the root of the world-record 28.8% efficiency held by an ELO thin-film GaAs cell with planar mirrored rear surface [9,10]. ELO thin-film InAs/GaAs QD cells with planar rear mirror were first reported in [34,35]. More recently, ELO thin-film cells with textured back surface reflectors have been reported in [26], demonstrating a 30% increase of QD current contribution compared to a cell with planar reflector.…”

Section: Introductionmentioning

confidence: 99%

Light-trapping enhanced thin-film III-V quantum dot solar cells fabricated by epitaxial lift-off

Cappelluti

Kim

Eerden³

et al. 2018

Solar Energy Materials and Solar Cells

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We report thin-film InAs/GaAs quantum dot (QD) solar cells with n − i − p + deep junction structure and planar back reflector fabricated by epitaxial lift-off (ELO) of full 3-inch wafers. External quantum efficiency measurements demonstrate twofold enhancement of the QD photocurrent in the ELO QD cell compared to the wafer-based QD cell. In the GaAs wavelength range, the ELO QD cell perfectly preserves the current collection efficiency of the baseline single-junction ELO cell. We demonstrate by full-wave optical simulations that integrating a micro-patterned diffraction grating in the ELO cell rearside provides more than tenfold enhancement of the near-infrared light harvesting by QDs. Experimental results are thoroughly discussed with the help of physics-based simulations to single out the impact of QD dynamics and defects on the cell photovoltaic behavior. It is demonstrated that non radiative recombination in the QD stack is the bottleneck for the open circuit voltage (V oc ) of the reported devices. More important, our theoretical calculations demonstrate that the V oc offest of 0.3 V from the QD ground state identified by Tanabe et al., 2012, from a collection of experimental data of high quality III-V QD solar cells is a reliable -albeit conservative -metric to gauge the attainable V oc and to quantify the scope for improvement by reducing non radiative recombination. Provided that material quality issues are solved, we demonstrate -by transport and rigorous electromagnetic simulations -that light-trapping enhanced thin-film cells with twenty InAs/GaAs QD layers reach efficiency higher than 28% under unconcentrated light, ambient temperature. If photon recycling can be fully exploited, 30% efficiency is deemed to be feasible.

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Section: Introductionmentioning

confidence: 99%

Light-trapping enhanced thin-film III-V quantum dot solar cells fabricated by epitaxial lift-off

Cappelluti

Kim

Eerden³

et al. 2018

Solar Energy Materials and Solar Cells

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“…Finally, the combination of a thin-film structure with light trapping techniques, which effectively increase the optical length of the devices, may lead to physically thin but optically thick (highly absorbent) solar cells [13]. Related to this, thin-film device processing has also caught the attention of researches working on solar cells based on nanostructures, such as inorganic quantum dot [14,15] or quantum well [16][17][18] solar cells. In those works, surface texturing [19] of thinfilm devices is explored as a means of enhancing lowenergy-photon absorption in the nanostructures.…”

Section: Introductionmentioning

confidence: 99%

A substrate removal processing method for III–V solar cells compatible with low-temperature characterization

Villa

Ramiro

Ripalda³

et al. 2017

Materials Science in Semiconductor Processing

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In this work, we present a substrate removal procedure for solar cells compatible with direct attachment of the epitaxy to a holder through a thermally and electrically conductive interface. In our case this procedure was motivated by the need to develop a processing technique compatible with lowtemperature characterization of the devices. The method is based on the use of indium to bond a thin-film epitaxial structure to a silicon support. The adequate properties of indium, namely, low tensile strength and good thermal and electrical conductivity, allow characterizing the devices at very low temperatures without causing strain-induced degradation in the samples. Following this method, we have fabricated and characterized thin-film (1.74 µm) AlGaAs solar cells with and without a layer of InAs quantum dots. We show the adequacy of our method to measure at low temperatures by means of measuring the photocurrent or quantum efficiency of the devices at different temperatures, ranging from 300 K to 20 K.

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“…4 The efficiency of pn junction solar cells can potentially be further improved by insertion of low-dimensional nanostructures, e.g., quantum wells (QWs), into a GaAs p-i-n photovoltaic cell structure so that J sc can be increased by extending the cell's absorption to longer wavelengths (>900 nm). [5][6][7][8][9] However, reports show that such approaches often result in a reduced V oc , as material defects can be introduced due to lattice mismatch 10,11 and carrier extraction efficiency can be lowered since QWs can function as recombination centers for photo-generated carriers. [12][13][14] To mitigate these effects, strain-balance techniques have been employed to minimize lattice relaxation during growth.…”

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confidence: 99%

Minimized open-circuit voltage reduction in GaAs/InGaAs quantum well solar cells with bandgap-engineered graded quantum well depths

Dasika

et al. 2014

Appl. Phys. Lett.

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The use of InGaAs quantum wells with composition graded across the intrinsic region to increase open-circuit voltage in p-i-n GaAs/InGaAs quantum well solar cells is demonstrated and analyzed. By engineering the band-edge energy profile to reduce photo-generated carrier concentration in the quantum wells at high forward bias, simultaneous increases in both open-circuit voltage and short-circuit current density are achieved, compared to those for a structure with the same average In concentration, but constant rather than graded quantum well composition across the intrinsic region. This approach is combined with light trapping to further increase short-circuit current density.

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Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

Cited by 16 publications

References 20 publications

Light-trapping enhanced thin-film III-V quantum dot solar cells fabricated by epitaxial lift-off

Light-trapping enhanced thin-film III-V quantum dot solar cells fabricated by epitaxial lift-off

A substrate removal processing method for III–V solar cells compatible with low-temperature characterization

Minimized open-circuit voltage reduction in GaAs/InGaAs quantum well solar cells with bandgap-engineered graded quantum well depths

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