Exploiting intervalley scattering to harness hot carriers in III–V solar cells


Hot carrier solar cells offer the potential to exceed the Shockley–Queisser limit. So far, however, there has been no clear route to achieve this result. Recently, the exploitation of the satellite valleys of the solar absorber material has been proposed as a feasible approach to harness hot carriers. Here, we show that, upon photoinduced and field-aided intervalley scattering to upper L-valleys, hot carriers can be harnessed in InGaAs/AlInAs heterojunctions at voltages defined by the upper valley (~1.25 V in the ideal case) rather than the bandgap of the InGaAs absorber (0.75 eV) under practical operational conditions. The efficiency of the present system does not exceed the single bandgap limit due to a mismatch in the valley degeneracy across the n+-AlInAs/n-InGaAs interface. However, we suggest that this is not a fundamental limitation to the realization of a hot carrier solar cell.

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Fig. 1: InGaAs band structure and sample schematic.
Fig. 2: Photoluminescence measurements with 442 nm and 1,064 nm excitation.
Fig. 3: JV measurements with 442 nm, 1,064 nm and 1-Sun illumination.
Fig. 4: Calculated band alignments and electric field distribution for several applied biases.
Fig. 5: Concentrated JV and comparison with optimal JV.

Data availability

All the data generated or analysed during this study are included in this published article and its Supplementary Information files. The data that support the plots within this paper are available from the corresponding authors upon reasonable request.


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The authors acknowledge financial support from the National Science Foundation ECCS program through grant no. ECCS-1610062. This work was performed under the umbrella of the Oklahoma Photovoltaics Research Institute (OKPVRI) and the Center for Quantum Research and Technology (CQRT) at the University of Oklahoma.

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The devices were processed by H.E. and K.R.D. The data were taken and analysed by a combination of H.E., K.R.D. and V.R.W. at OU. Theoretical calculations were performed by D.K.F. at ASU. The materials were grown by molecular beam epitaxy at OU by T.D.M. under the supervision of M.B.S. All experimental work was performed in the group of I.R.S., whom also provided scientific and technical guidance, as well as project management. The manuscript was written by a combination of V.R.W., I.R.S. and D.K.F.

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Correspondence to Ian R. Sellers.

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Supplementary Information

Supplementary Figs. 1−6, discussion and refs. 1–2.

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Esmaielpour, H., Dorman, K.R., Ferry, D.K. et al. Exploiting intervalley scattering to harness hot carriers in III–V solar cells. Nat Energy 5, 336–343 (2020). https://doi.org/10.1038/s41560-020-0602-0

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