Interstitial Light Trapping and Optical Confinement in Multijunction Solar Cells

We recently demonstrated an ultra-thin solar cell with increased radiation tolerance as compared to a traditionally thick absorber counterpart. However, as the active region of the device was reduced so was the absorption with respect to state of the art devices. Therefore, we discuss a light trapping design, which implements nanosphere natural photolithography to fabricate a micropillared diffraction grating, combined with a transparent spacer layer and a distributed Bragg reflector. We discuss the fabrication process and illustrate the effectiveness of integrating light trapping structures for enhanced optical confinement within an ultra-thin solar cell design.