Nanoscale engineering: optimizing electron-hole kinetics of quantum dot solar cells

K. A. Sablon; V. Mitin; A. Sergeev; J. W. Little; N. Vagidov; K. Reinhardt; K. A. Olver

doi:10.1117/12.883307

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17 May 2011 Nanoscale engineering: optimizing electron-hole kinetics of quantum dot solar cells

K. A. Sablon, V. Mitin, A. Sergeev, J. W. Little, N. Vagidov, K. Reinhardt, K. A. Olver

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Proceedings Volume 8035, Energy Harvesting and Storage: Materials, Devices, and Applications II; 80350M (2011) https://doi.org/10.1117/12.883307
Event: SPIE Defense, Security, and Sensing, 2011, Orlando, Florida, United States

Abstract

We report the substantial increase in power efficiency in InAs/GaAs quantum dot (QD) solar cells due to n-doping of the inter-dot space in p⁺-δ-n⁺ structures and investigate the physical mechanisms that provide this significant improvement. We have compared the GaAs reference cell to undoped, n-doped and p-doped QD solar cell structures and found that the short circuit current, J_SC, of the undoped QD solar cell is comparable to that of the GaAs reference cell. On the other hand, while p-doping deteriorates the device performance, n-doping significantly increases J_SC without degradation of the open circuit voltage, V_OC. The photovoltaic device, n-doped to provide approximately six electrons per dot, demonstrates 60% increase in J_SC, from 15.07 mA/cm² to 24.30 mA/cm². Strong increase in the photoresponse and J_SC of the IR portion of the solar spectrum has been observed for the n-doped structures. From the photoluminescence data, the electron capture noticeably dominates over hole capture leading to an accumulation of electrons in the dots. We have observed that QDs with built-in charge (Q-BIC) enhances harvesting of IR energy, suppresses the fast electron capture process, and stabilizes the open circuit voltage. All of these factors lead to a significant improvement of the cell efficiency.

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K. A. Sablon, V. Mitin, A. Sergeev, J. W. Little, N. Vagidov, K. Reinhardt, and K. A. Olver "Nanoscale engineering: optimizing electron-hole kinetics of quantum dot solar cells", Proc. SPIE 8035, Energy Harvesting and Storage: Materials, Devices, and Applications II, 80350M (17 May 2011); https://doi.org/10.1117/12.883307

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