Quantum dot solar cells have gained attention in the last years as one of the most promising implementations of the intermediate band solar cell concept, for which according to theoretical calculations based on the detailed balance principle, an efficiency above 63% under maximum sunlight concentration is predicted. Layers of quantum dots embedded within the intrinsic region of a p-i-n solar cell introduce energy states, which play the role of intermediate levels and extend the light harvesting by allowing the absorption of sub-bandgap photons. The extraction of the carriers photogenerated in the confined states and subsequent collection in the contacts lead to an increase in the short-circuit current of the solar cell that, according to all reported experiments, is always accompanied by a reduction in the open-circuit voltage that prevents an improvement of the efficiency with respect to bulk devices. The poor performance of the quantum dot solar cells has encouraged the investigation of these devices from the modeling and simulation perspectives. The models usually applied are based on the intermediate band theory and are not able to offer reliable results, as the intersubband carrier transfer processes involving the quantum dot states are neglected. In this thesis, a physics-based model for the simulation of quantum dot solar cells is developed and applied to the comprehensive study of their performance, with particular focus on cells based on III-V semiconductor materials. The dependence of the electrical and optical characteristics of these devices on different physical parameters, design features and operation conditions is thoroughly analyzed. The model combines drift-diffusion equations for bulk transport and phenomenological rate equations for carrier dynamics in the QDs. In contrast to other existing approaches, the developed model takes into account the carrier transitions between the confined states introduced by the QDs and also considers reasonable absorption distributions for the nanostructures, which lead to more realistic simulation results. This is supported by the very good agreement with experimental data.

Physics based modeling and numerical simulation of III-V quantum dot solar cells / Cedola, ARIEL PABLO. - (2016).

Physics based modeling and numerical simulation of III-V quantum dot solar cells

CEDOLA, ARIEL PABLO
2016

Abstract

Quantum dot solar cells have gained attention in the last years as one of the most promising implementations of the intermediate band solar cell concept, for which according to theoretical calculations based on the detailed balance principle, an efficiency above 63% under maximum sunlight concentration is predicted. Layers of quantum dots embedded within the intrinsic region of a p-i-n solar cell introduce energy states, which play the role of intermediate levels and extend the light harvesting by allowing the absorption of sub-bandgap photons. The extraction of the carriers photogenerated in the confined states and subsequent collection in the contacts lead to an increase in the short-circuit current of the solar cell that, according to all reported experiments, is always accompanied by a reduction in the open-circuit voltage that prevents an improvement of the efficiency with respect to bulk devices. The poor performance of the quantum dot solar cells has encouraged the investigation of these devices from the modeling and simulation perspectives. The models usually applied are based on the intermediate band theory and are not able to offer reliable results, as the intersubband carrier transfer processes involving the quantum dot states are neglected. In this thesis, a physics-based model for the simulation of quantum dot solar cells is developed and applied to the comprehensive study of their performance, with particular focus on cells based on III-V semiconductor materials. The dependence of the electrical and optical characteristics of these devices on different physical parameters, design features and operation conditions is thoroughly analyzed. The model combines drift-diffusion equations for bulk transport and phenomenological rate equations for carrier dynamics in the QDs. In contrast to other existing approaches, the developed model takes into account the carrier transitions between the confined states introduced by the QDs and also considers reasonable absorption distributions for the nanostructures, which lead to more realistic simulation results. This is supported by the very good agreement with experimental data.
2016
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2642829
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