Visible-light-enhanced Mechanical Energy Harvesting using Polarization-Graded InGaN Nanorod Piezoelectric Nanogenerators

Piezoelectricity in wide band-gap III-nitride semiconductors is believed to have great potential for harvesting mechanical energy from our living environments. However, under visible-light illumination, the direct band gap of III-nitrides results in very high generation rate of photon-excited free carriers which in turn leads to easily screen the piezoelectric field, which would remarkably decrease the piezoelectric performance of III-nitrides nanorod nanogenerators. Here we proposed a vertically integrated nanogenerator (VING) with polarization-graded InGaN nanorods have high output voltage/current (~3V/~100 nA) and can be further increased under red and green light illumination, totally avoid the disaster of screen effect. The results could assist the design of energy harvesting processes that are more energy efficient and compact than current hybrid solar/piezoelectric nanogenerators.