Intermediate Band Solar Cell with Extreme Broadband Spectrum Quantum Efficiency

Datas, Alejandro; López, E.; Ramiro, I.; Antolín, E.; Martı́, Antonio; Ĺuque, A.; Tamaki, Ryo; Yoshida, Shoji; Sogabe, Tomah; Okada, Yoshitaka

doi:10.1103/physrevlett.114.157701

Cited by 68 publications

(38 citation statements)

References 17 publications

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“…Hence, for the case of the IBSC, the absorption of two below bandgap energy photons to create one electronhole pair has been demonstrated, for example, in several implementations that use III-V semiconductor quantum dots [11][12][13][14][15]. In addition, it has also been proved that the presence of the intermediate band does not limit the output voltage of the cell [16,17].…”

Section: Brief Review Of the Status Of Empirical Research On Novel Comentioning

confidence: 98%

Limiting Efficiencies of Novel Solar Cell Concepts in Space

et al. 2017

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In this work we study the limiting efficiency in space environmental conditions of three novel solar cell concepts (hot carrier solar cells, multiple exciton generation solar cells and intermediate band solar cells) and how this limiting efficiency is impacted by the temperature and degradation due to radiation. Comparisons are made with state of the art triplejunction solar cells whose performance is taken as reference. In the last section of the work we briefly review the status related to the experimental achievements of these cells to date. NOVEL SOLAR CELL CONCEPTS OVERVIEWIn order to exceed the limiting efficiency of single gap solar cells, three novel solar cell approaches have been proposed: the hot carrier solar cell (HCSC), the multiple exciton generation solar cell (MEGSC) and the intermediate band solar cell (IBSC).In the HCSC (Fig. 1a) photons (hv) create electron-holepairs. However, the excited electrons and holes are not allowed to interact with the semiconductor lattice so that they do not cool down and, therefore, they do not lose their energy in thermalization processes with the semiconductor lattice. It is from this property that the HCSC heritages its efficiency advantage over single gap solar cells. The extraction of these hot electrons and holes from the solar cell demands, however, the use of special contacts (named energy selective contacts) in order to make possible that electrons cool down reversibly to the contact temperature at the time they increase their electro-chemical potential. In the multiple exciton generation solar cell (MEGSC, Fig. 1b) high energy photons (hv) create high energy excited electron-hole pairs (or excitons). This pairs do not ideally lose their energy through thermalization processes but, instead, create one or more additional electron-hole pairs (e1-h1; e2-h2, e3-h3) depending on how many times their energy exceeds the energy of the gap. The MEGSC, proposed by Nozik [4], is an evolution of the impact ionization solar cell (IISC) proposed by Werner, Brendel and Queisser [5]. The difference relies on the fact that, while the IISC was thought to be implemented in bulk semiconductors, the MEGSC is envisaged to be implemented using quantum dots. By using quantum dots, the probability of one photon creating more than one electron-hole pair is increased because the momentum conservation selection rule is not required.The intermediate band solar cell (IBSC) is based on the idea of implementing a semiconductor like material that, instead of exhibiting one single gap, it would exhibit two bandgaps (Fig. 1c). The two bandgaps appear when an "intermediate band" (IB) is created inside a conventional high bandgap semiconductor host. This IB allows the absorption of below bandgap energy photons that, in conventional solar cells are wasted. This absorption occurs through the successive promotion of electrons from the valence band (VB) to the IB and from the IB to the conduction band (CB). Thanks to the formation of the additional bandgap, the IBSC is capable of perform...

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Section: Brief Review Of the Status Of Empirical Research On Novel Comentioning

confidence: 98%

Limiting Efficiencies of Novel Solar Cell Concepts in Space

et al. 2017

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“…42 Based on this model, Δ opt depends linearly on the fluence of 0.8-eV photons because the addition of an optical escape pathway reduces the mean time carriers spent in traps in either the QD or wetting layer and, therefore, increases the conductivity (therefore, the photocurrent) even for a fixed number of carriers. 30 It is worthwhile to mention here that in a recent work, Asahi et al 45 have reported a saturation of two-step photocurrents. However, unlike the work reported here involving the two-step photoexcitation from valence band to intermediate states and from intermediate states to conduction band, Asahi et al 45 observed the saturation by tuning "two-step" photoexcitation from valance band to conduction band and from intermediate states to conduction band.…”

Section: Carrier Escape Nature and Electric Field Effectmentioning

confidence: 99%

“…30,32,34,37,47 Under the ideal case, the device is assumed to be defect-free; therefore, the SRH or NR recombination will be completely eliminated. As discussed in Sec.…”

Section: 4248mentioning

confidence: 99%

Recent progress on quantum dot solar cells: a review

2016

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Abstract. Semiconductor quantum dots (QDs) have a potential to increase the power conversion efficiency in photovoltaic operation because of the enhancement of photoexcitation. Recent advances in self-assembled QD solar cells (QDSCs) and colloidal QDSCs are reviewed, with a focus on understanding carrier dynamics. For intermediate-band solar cells using selfassembled QDs, suppression of a reduction of open circuit voltage presents challenges for further efficiency improvement. This reduction mechanism is discussed based on recent reports. In QD sensitized cells and QD heterojunction cells using colloidal QDs well-controlled heterointerface and surface passivation are key issues for enhancement of photovoltaic performances. The improved performances of colloidal QDSCs are presented. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…1,3 Thus, the proposed implementation of QD-IBSCs must accompany an efficient two-step carrier generation via IB states, however, it has been a challenge to notably demonstrate this operation principle particularly at room temperature, 5 which is owed to a relatively small optical generation rate from the QD-IB states to CB. The rate of thermal escape of electrons from IB to CB continuum as well as recombination from CB to IB transitions (reverse process) increases significantly with increasing temperature, [6][7][8] and these processes inevitably lead to a drop in the open-circuit voltage V OC and eventually outweigh the current gained by QD absorption.…”

Section: Introductionmentioning

confidence: 99%

Effect of Si doping and sunlight concentration on the performance of InAs/GaAs quantum dot solar cells

et al. 2017

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Abstract. For intermediate band solar cells, the control of the carrier filling ratio in intermediate band is important to achieve high efficiency. We have investigated the effect of carrier doping of InAs/GaAs quantum dots (QDs) with Si and sunlight concentration on the quantum dots solar cell (QDSC) characteristics. The prefilling by Si doping of InAs/GaAs QDs was performed using two methods: modulation or δ-doping and direct doping. A gradual recovery in the open-circuit voltage with increasing Si doping concentration was observed, and it suggested a decrease of recombination via Si-doped QD states. Under high-concentrated sunlight illumination, QD states were additionally filled with photocarriers, and the open-circuit voltage increased nonlinearly with concentration ratio in both the nondoped and Si-doped QDSCs. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Intermediate Band Solar Cell with Extreme Broadband Spectrum Quantum Efficiency

Cited by 68 publications

References 17 publications

Limiting Efficiencies of Novel Solar Cell Concepts in Space

Limiting Efficiencies of Novel Solar Cell Concepts in Space

Recent progress on quantum dot solar cells: a review

Effect of Si doping and sunlight concentration on the performance of InAs/GaAs quantum dot solar cells

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