Voltage recovery in intermediate band solar cells

• Published in: Solar energy materials and solar cells 2012-03, Vol.98, p.240-244
• Main Authors: Linares, Pablo G., Martí, Antonio, Antolín, Elisa, Farmer, Corrie D., Ramiro, Íñigo, Stanley, Colin R., Luque, Antonio
• Format: Article
• Language: English
• Subjects: Applied sciences; Concentrated light; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Exact sciences and technology; Intermediate band; Natural energy; Photoelectric conversion; Photovoltaic conversion; Quantum dots; Recombination; Solar cell; Solar cells. Photoelectrochemical cells; Solar energy
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2011.11.015

The intermediate band solar cell (IBSC) is based on a novel photovoltaic concept and has a limiting efficiency of 63.2%, which compares favorably with the 40.7% efficiency of a conventional, single junction solar cell. It is characterized by a material hosting a collection of energy levels within its bandgap, allowing the cell to exploit photons with sub-bandgap energies in a two-step absorption process, thus improving the utilization of the solar spectrum. However, these intermediate levels are often regarded as an inherent source of supplementary recombination, although this harmful effect can in theory be counteracted by the use of concentrated light. We present here a novel, low-temperature characterization technique using concentrated light that reveals how the initially enhanced recombination in the IBSC is reduced so that its open-circuit voltage is completely recovered and reaches that of a conventional solar cell. ▶ An InAs/GaAs quantum dot intermediate band solar cell (IBSC) and a GaAs control solar cell are designed and fabricated. ▶ A novel characterization technique consisting of low temperature and concentrated light JL–VOC is implemented. ▶ The IBSC and the control cell are measured with this technique. ▶ Phenomenon known as “voltage preservation” in an IBSC is experimentally demonstrated.