Enhanced Performance of GaAs Solar cell on Roll-to-Roll Processed Flexible Epi-Ready Metal Tape by Hydrogen Passivation

We have demonstrated GaAs single-junction solar cells on epi-ready low-cost flexible metal tape and studied the impact of hydrogen passivation. In our process, single-crystalline-like germanium films are grown on flexible metal tape over which epitaxial (Al)GaAs semiconductor thin films are grown by metal organic chemical vapor deposition (MOCVD). As-deposited GaAs comprises of micrometer-sized grains with a high density of low-angle grain boundaries (<; 1° misorientation) which results in active recombination centers. To improve the conversion efficiency of these flexible GaAs solar cells, grain boundary passivation technique was used which decreases the leakage current by making grain boundaries electrically inactive. Open Circuit Voltage (V
_OC
) was found to increase from 380mV to 806mV and leakage current was reduced by two orders of magnitude after passivation.