Influence of wetting layers and quantum dot size distribution on intermediate band formation in InAs/GaAs superlattices

Huang, Simon; Semichaevsky, Andrey; Webster, L. A.; Johnson, Harley T.; Goldman, R. S.

doi:10.1063/1.3631785

Cited by 19 publications

(6 citation statements)

References 22 publications

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“…According to ideal theoretical predictions, the IBSC is expected to exhibit extremely high conversion efficiency, >60%, under the maximum concentration and 48.2% under one-sun irradiation5. Substantial progress has been made in this field101112131415161718192021222324252627 since Luque and Martí have proposed this concept of IBSC in 1997 (ref. 5).…”

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confidence: 99%

Two-step photon up-conversion solar cells

et al. 2017

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Reducing the transmission loss for below-gap photons is a straightforward way to break the limit of the energy-conversion efficiency of solar cells (SCs). The up-conversion of below-gap photons is very promising for generating additional photocurrent. Here we propose a two-step photon up-conversion SC with a hetero-interface comprising different bandgaps of Al0.3Ga0.7As and GaAs. The below-gap photons for Al0.3Ga0.7As excite GaAs and generate electrons at the hetero-interface. The accumulated electrons at the hetero-interface are pumped upwards into the Al0.3Ga0.7As barrier by below-gap photons for GaAs. Efficient two-step photon up-conversion is achieved by introducing InAs quantum dots at the hetero-interface. We observe not only a dramatic increase in the additional photocurrent, which exceeds the reported values by approximately two orders of magnitude, but also an increase in the photovoltage. These results suggest that the two-step photon up-conversion SC has a high potential for implementation in the next-generation high-efficiency SCs.

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confidence: 99%

Two-step photon up-conversion solar cells

et al. 2017

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“…Recently, quantum dots have been used to drive the absorption range, extending into the sub‐band gap . The short‐circuit current ( J SC ) is relevant to the dot size, size nonuniformity, shape, and dot materials . In addition, it is also associated with the number of QD layers and the dot volume density .…”

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confidence: 99%

Efficiency of quantum dot solar cell enhanced by improving quantum dots performance

Weng

Ueng

Lee

2014

Phys. Status Solidi A

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We propose an innovative description to provide a quantitative basis to enhance the conversion efficiency of InAs/GaAs quantum dot solar cells (QDSC). A theoretical approach and numerical simulation are used to improve the performance of the quantum dots and analyze the relevance to enhance the conversion efficiency. The absorption coefficient of QDs is determined in terms of dot material, dot size, size dispersion, and shape, which are used to obtain a better match between the absorption spectrum of QDs with the portion of the solar spectrum. Either increasing the surface density for raising the photocurrent or enlarging the dot size for matching well the solar spectrum is a trade-off issue. The influence of surface density, spacer thickness, and number of dot layers on the opencircuit voltage and efficiency is discussed in detail. Moreover, volume fraction can be taken as a balance reference for the counteracting effect between J SC and V OC .

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“…[10][11][12] Since the carrier depletion occurs primarily for InAs coverage beyond 3 monolayers (ML), it is often attributed to strain relaxation-induced defects which act as carrier traps. 13,14 However, for C-V and scanning capacitance microscopy, n is spatially averaged over 100s of nm 2 and lm 2 , i.e., 10-100 000 QDs. Thus, carrier concentration profiling across a single QD and the surrounding 2D alloy layer, often termed the "wetting layer" (WL), has not been reported.…”

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confidence: 99%