Thermal survivability characterization of quantum dot multi-junction photovoltaic cells

The goal of our lab, the Advanced Space Power Generation group, is to research and improve energy technology for use in the space environment. We have tested the thermal survivability of quantum dot (QD) photovoltaic cells by heating samples to increasing temperatures until failure. Between cycles of heating we analyzed changes in the cells by measuring their current-voltage response to a solar simulator and quantifying electroluminescence with spectroscopy. An important design consideration for solar cells is material band gap energy, which determines which layers can absorb photons with specific wavelengths and how much energy can be converted from those photons. To better absorb the solar spectrum, the tested QD cells use layers of InAs quantum dots to alter the photon absorption of the middle cell in order to produce more current. Annealing at high temperatures reduced the material quality of the solar cells, eventually rendering the samples ineffective.