Prof. Tervo gave an invited talk at the 15th World Conference on Thermophotovoltaic Generation of Electricity (TPV-15) in Madrid, Spain, titled “Narrow-Gap Intersubband Thermophotovoltaic Cells.” This described a new type of quantum-engineered PV cell that can achieve narrow effective bandgaps using wider-bandgap materials, which could lead to efficient and power-dense ways of converting low-temperature heat sources to electricity.