Photovoltaic Cell Based on n-ZnO Microrods and p-GaN Film

Abstract

A photovoltaic cell based  on  p-GaN film/n-ZnO microrods quasi-array heterojunction  was fabricated  and  investigated  for  the  first time  for  harvesting  energy  from  a  near-ultraviolet  source (395–400 nm). The source was a commercially available indoor light-emitting diode. According to the scanning electron microscopy data, the ZnO array consisted of tightly packed vertical microrods with a diameter of approximately 2–3 µm. The turn-on voltage of the heterojunction of ZnO/GaN (rods/film) was around 0.6 V. The diode-ideality factor was estimated to be of around 4. The current–voltage characteristic of the photovoltaic cell under near-ultraviolet illumination showed an open-circuit voltage of 0.26 V, a short-circuit current of 0.124 nA, and a fill factor of 39%, resulting in an overall efficiency of 1.4 x 10^-5%. These results may be useful in the engineering of electronic devices based on the materials with optical transparency.