Wladek Walukiewicz
Materials Sciences Division
Lawrence Berkeley National Laboratory
Abstract:
In the presentation I will discuss the current status of research
and development of high efficiency solar cells. After brief review of the fundamentals
of different types of cells I will discuss our work on new materials for multijunction
and multiband devices.
We have discovered recently, that the band gaps of GaxIn1-xN alloys
span energies from 0.7 to 3.4 eV, providing an almost perfect match to the solar
spectrum. This offers an interesting possibility of using this alloy system
for high efficiency multijunction solar cells. I will discuss recent progress
and remaining challenges to implementation of the nitride alloys for high efficiency
multijunction solar cells.
In the second part of the talk I will present recent progress on utilization of multiband semiconductors for high efficiency solar cells. We have used ion implantation and pulsed laser melting to synthesize ZnOTe and GaNAsP alloys with a mid gap intermediate band. The band serves as “stepping stone” broadening the range of optical transitions and leading to better utilization of the full solar spectrum. The alloys can be used to produce simple, single junction high efficiency cells