TiO2 nanotubes antireflection coating design for GaAs solar cells

Abstract

The results of the optimization of antireflection films of TiO2 nanotubes on GaAs solar cells, non-encapsulated and encapsulated, are presented. The ARC forms a bilayer of porous TiO2 over a dense bottom. The films were prepared on Si and GaAs substrates via a versatile electrochemical anodization process which produces films with good optical performance. The thicknesses and porosity of the ARC were optimized numerically with a method based on maximizing the short circuit current. Using experimental indices, the minimum Rw was 1.81% for the non-encapsulated case. For the encapsulated case, the lowest Rw was 2.34%, where the porosity of the top layer was adjusted in addition to the thicknesses. In simulations of a GaAs solar cell, the addition of the optimized ARC resulted in a Jsc increase of 43.6% for the non-encapsulated case, and 36.7% for the encapsulated case.