The industrial sector consumes one third of its total incoming energy and the remaining energy is discharged as wasted heat. Here, we experimentally demonstrate Thermally Enhanced Photoluminescence device for harvesting industrial wasted heat using low band gap photovoltaics. Specifically, the emission of a low band gap photoluminescence material excited next to its band edge and is heated in parallel, is characterized by a conserved photon flux of a blue-shift emission that can be coupled to a higher bandgap PV generating enhanced electricity due to the high operating voltage. The efficiency of such concept is orders of magnitude higher than the efficiency of thermal emission at the same temperature. Using a hot plate at 50oC-100oC as a heat source and Er:Tm doped silica, we have observed the absorption at a spectral range between 1.6 um and 1.9 um that is followed by a blue-shifted photoluminescence at 1.6 um that can be efficiently coupled to GaInAs or Ge solar cell. Using efficient LED and solar cell can result in a pseudo “perpetual motion” where the excessive heat together with the LED pump generates electric power exceeding the LED power consumption. This device can be extended for harvesting solar radiation between 1µm and 2 µm, which is considered as wasted radiation. Theoretical result shows that the ideal system can reach up to 28% efficiency cells, overcoming thermo-electrics concepts.
|