AlGaAs/GaAs photovoltaic cells with an array of InGaAs QDs

Blokhin, S. A.; Sakharov, A. V.; Nadtochy, A. M.; Pauysov, Alexey S.; Maximov, M. V.; Ledentsov, N. N.; Kovsh, A. R.; Mikhrin, S.; Lantratov, V. M.; Mintairov, S. A.; Kaluzhniy, N. A.; Shvarts, М. Z.

doi:10.1134/s1063782609040204

Cited by 155 publications

(142 citation statements)

References 8 publications

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“…Thus, although the cell current increased, its voltage was limited to the GaNAs bandgap. Other groups have also made IB solar cells based on QDs 1420 ; Blokhin et al 17 and we might expect that each QD absorbs light rather effectively. Modelling becomes necessary to gain a deeper insight of this issue.…”

Section: Quantum Dot Ib Solar Cellsmentioning

confidence: 99%

Understanding intermediate-band solar cells

2012

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The intermediate-band solar cell is designed to provide a large photogenerated current while maintaining a high output voltage. To make this possible, these cells incorporate an energy band that is partially filled with electrons within the forbidden bandgap of a semiconductor. Photons with insufficient energy to pump electrons from the valence band to the conduction band can use this intermediate band as a stepping stone to generate an electron-hole pair. Nanostructured materials and certain alloys have been employed in the practical implementation of intermediate-band solar cells, although challenges still remain for realizing practical devices. Here we offer our present understanding of intermediate-band solar cells, as well as a review of the different approaches pursed for their practical implementation. We also discuss how best to resolve the remaining technical issues.T he intermediate-band (IB) solar cell consists of an IB material sandwiched between two ordinary n-and p-type semiconductors 1 , which act as selective contacts to the conduction band (CB) and valence band (VB), respectively (Fig. la). In an IB material, sub-bandgap energy photons are absorbed through transitions from the VB to the IB and from the IB to the CB, which together add up to the current of conventional photons absorbed through the VB-CB transition. In 1997 2 , researchers used hypotheses similar to those adopted by Shockley and Queisser in 1961 3 to derive a detailed balance-limiting efficiency of 63% for the IB solar cell, at isotropic sunlight illumination (concentration of 46,050 suns) and assuming Sun and Earth temperatures to be 6,000 K and 300 K, respectively (Fig. lb). This work also presented the Shockley-Queisser limiting efficiency of 41% for single-gap solar cells operating under the same conditions 2 . The limiting efficiency of the IB solar cell is similar to that of a triple-junction solar cell connected in series. However, the IB can be regarded 4 as a set of two cells connected in series (corresponding to the VB-IB and IB-CB transitions) and one in parallel (corresponding to the VB-CB transition). This provides the IB solar cell with additional tolerance to changes in the solar spectrum.An optimal IB solar cellhas a total bandgap of about 1.95 eV, which is split by the IB into two sub-bandgaps of approximately 0.71 eV and 1.24 eV The quasi-Fermi levels (QFLs) or electrochemical potentials of the electrons in the different bands are usually close to the edges of the bands. Because the voltage of any solar cell is the difference between the CB QFL at the electrode in contact with the n-type side and the VB QFL at the electrode in contact with the p-type side, the maximum photovoltage of the IB solar cell is limited to 1.95 eV, although it is still capable of absorbing photons of energy above 0.71 eV In contrast, single-gap solar cells cannot supply a voltage greater than the lowest photon energy they can absorb. IB solar cells can deliver a high photovoltage by absorbing two subbandgap photons to produce one high ...

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Section: Quantum Dot Ib Solar Cellsmentioning

confidence: 99%

Understanding intermediate-band solar cells

2012

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“…This means that carrier relaxation within the bands (thermalization) is a much faster process than carrier relaxation between bands (recombination). Also, two layers of conventional semiconductor of opposite doping (p-emitter and n-emitter) tral photocurrent or quantum efficiency (QE) measurements on In(Ga)As/GaAs QD-IBSCs reported thus far [5][6][7][8][9][10][11][12] show SBG photocurrent in that spectral range. The point to emphasize here is that the SBG photocurrent measured in QE experiments on QD-IBSCs constitutes a proof of strong IB-CB carrier escape, because by illuminating exclusively in the E H -E G spectral range only the VB-IB transition is optically excited.…”

Section: Basic Ibsc Model and Implementation With Qdsmentioning

confidence: 99%

“…One approach that is being followed to implement the IBSC is the use of quantum dots (QDs), 4 most frequently In(Ga)As/GaAs QD arrays. [5][6][7][8][9][10][11] The QD-IBSC prototypes fabricated with this system have served to demonstrate the operation principles of the IBSC model 12 ' 13 but they still suffer from parasitic loss mechanisms. In particular, it has been found that the respective electronic populations of the intermediate band (IB) and the conduction band (CB) cannot be split sufficiently.…”

Section: Introductionmentioning

confidence: 99%

Reducing carrier escape in the InAs/GaAs quantum dot intermediate band solar cell

Antolín

Martı́

Farmer

et al. 2010

Journal of Applied Physics

165

136

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Intermediate band solar cells (IBSCs) fabricated to date from In(Ga)As/GaAs quantum dot arrays (QD-IBSC) exhibit a quantum efficiency (QE) that extends to below bandgap energies. However, the production of sub-bandgap photocurrent relies often on the thermal and/or tunneling escape of carriers from the QDs, which is incompatible with preservation of the output voltage. In this work, we test the effectiveness of introducing a thick GaAs spacer in addition to an InAlGaAs strain relief layer (SRL) over the QDs to reduce carrier escape. From an analysis of the QE at different temperatures, it is concluded that escape via tunneling can be completely blocked under short-circuit conditions, and that carriers confined in QDs with an InAlGaAs SRL exhibit a thermal escape activation energy over 100 meV larger than in the case of InAs QDs capped only with GaAs.

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“…Currently, QDs widely used in active area of lasers and allow increasing the radiation wavelength, improving thermal stability and reducing the threshold current, compared with traditional devices. However, first successful results of the application QDs in photovoltaic began publishing only recently and demonstrate the expansion of spectral sensitivity of the SC via photoelectric effect in InAs/GaAs QD [6][7][8]. In these works a noticeable but small contribution of QDs to the internal quantum efficiency of single-junction SC has been obtained.…”

Section: Introductionmentioning

confidence: 96%

The investigation of InGaAs quantum dot growth peculiarities for GaAs intermediate band solar cells

Salii

Mintairov

et al. 2018

J. Phys.: Conf. Ser.

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The dependence of the wavelength on MBE growth parameters of GaAs quantum dot in AlGaAs NWs on Si (111) substrate R R Reznik, I V Shtrom, Yu B Samsonenko et al. Abstract. In this work the growth peculiarities of InGaAs quantum dots (QDs) on GaAs surface have been investigated by metal-organic vapor-phase epitaxy (MOVPE). The influence of the main structural parameters, such as the amount of deposited InGaAs material and the thickness of the GaAs cap layer, on the optical properties of QDs has been considered. For these parameters the optimal values at which achieved the best photoluminescence intensity of QDs embedded into the matrix of the GaAs-based light-emitting structure have been established. The possibility of using several layers of QDs with the preservation of the optical properties of the investigated structures has been demonstrated. The design of solar cell (SC) based on GaAs with QD arrays in the active area has been proposed. It was shown that 20 layers of QDs embedded into the proposed SC structure contribute to the photogenerated current up to 0.97 mA/cm 2 for AM0 spectra and up to 0.77 mA/cm 2 for AM1.5D spectra, while maintaining the high quality of the p-n junction.

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AlGaAs/GaAs photovoltaic cells with an array of InGaAs QDs

Cited by 155 publications

References 8 publications

Understanding intermediate-band solar cells

Understanding intermediate-band solar cells

Reducing carrier escape in the InAs/GaAs quantum dot intermediate band solar cell

The investigation of InGaAs quantum dot growth peculiarities for GaAs intermediate band solar cells

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