Massachusetts Institute of Technology

Parthiban Santhanam

Rajeev J Ram

Dodd Joseph Gray

Contrary to conventional wisdom, which holds that light-emitting diodes (LEDs) should be cooled to increase efficiency, the LEDs disclosed herein are heated to increase efficiency. Heating an LED operating at low forward bias voltage (e.g., V&#x3c;kT/q) can be accomplished by injecting phonons generated by non-radiative recombination back into the LED's semiconductor lattice. This raises the temperature of the LED's active rejection, resulting in thermally assisted injection of holes and carriers into the LED's active region. This phonon recycling or thermo-electric pumping process can be promoted by heating the LED with an external source (e.g., exhaust gases or waste heat from other electrical components). It can also be achieved via internal heat generation, e.g., by thermally insulating the LED's diode structure to prevent (rather than promote) heat dissipation. In other words, trapping heat generated by the LED within the LED increases LED efficiency under certain bias conditions.

Thermo-electrically pumped light-emitting diodes

Phonon-recycling light-emitting diodes

Contrary to conventional wisdom, which holds that light-emitting diodes (LEDs) should be cooled to increase efficiency, the LEDs disclosed herein are heated to increase efficiency. Heating an LED operating at low forward bias voltage can be accomplished by injecting phonons generated by non-radiative recombination back into the LED's semiconductor lattice. This raises the temperature of the LED's active rejection, resulting in thermally assisted injection of holes and carriers into the LED's active region. This phonon recycling or thermo-electric pumping process can be promoted by heating the LED with an external source (e.g., exhaust gases or waste heat from other electrical components). It can also be achieved via internal heat generation, e.g., by thermally insulating the LED's diode structure to prevent (rather than promote) heat dissipation. In other words, trapping heat generated by the LED within the LED increases LED efficiency under certain bias conditions.

Growing community of inventors

Cambridge, MA, United States of America

Parthiban Santhanam