Effect of Low-Angle Grain-Boundary Passivation in Flexible Single-Crystal-Like Thin-Film GaAs Solar Cells

We theoretically and experimentally study the effect of defect-state passivation at low-angle grain boundaries (LA-GBs) on the photovoltaic performance characteristics of flexible single-crystal-like thin-film GaAs SCs. The 2D modeling of the SCs shows that LA-GBs in the single-crystal-like GaAs still limit their performance, especially for open-circuit voltage (V-OC), and effective passivation of the LA-GBs can boost the photoconversion efficiency remarkably. Two physical hydrogen-based passivation techniques and a chemical sulfide treatment are employed for the passivation of the LA-GBs in the single-crystallike GaAs. Current-voltage (I-V) and photoluminescence (PL) characterization studies demonstrate that sulfur by trioctylphosphine sulfide (TOP:S) solution passivation treatment can significantly increase PL peak intensity and the performance characteristics of flexible single-crystal-like GaAs SCs. A substantial improvement is achieved with increases of similar to 20%, similar to 10%, similar to 13%, and similar to 65% for V-OC, short-circuit current (J(SC)), fill factor (FF), and overall efficiency, respectively.