October 31, 2011 — Georgia Institute of Technology (Georgia Tech) researchers have found that gallium nitride (GaN) light emitting diodes (LEDs) get a significant efficiency boost from zinc oxide (ZnO) microwires. The piezo-phototronic effect charges LEDs’ ability to convert electricity to ultraviolet (UV) light, which GA Tech believes is a first for the LED industry.
Piezo-phototronics is the control of an optoelectronic device with piezoelectric potential. In this study, the ZnO crystals become electrically charged when its polarized ions are compressed or otherwise mechanically strained. Georgia Tech notes that piezoelectric and semiconducting materials can be tuned mechanically, opening up various device design improvement opportunities.
Mechanical strain brought out the piezoelectric potential in the wires, which then allowed researchers to tune the charge transport at the p-n junction and enhance carrier injection in the LEDs. The rate at which electrons and holes recombined to generate photons increased.