SPLTRAK Abstract Submission
External Quantum Efficiency and Device Reflectance of CIGS PV for Terrestrial and Space Based Applications
Bishal Shrestha, Indra Subedi, Nikolas Jacob Podraza
The University of Toledo, Toledo, OH, United States

Photovoltaic (PV) devices implemented for terrestrial and space applications suffer performance losses related to optical and thermal effects. One of the key factors reducing the performance of such devices is the front face reflection of the incident light that limits the number of current generating photons reaching the absorber layer, lowering short-circuit current density (Jsc). Photons absorbed in other component layers of the PV device that do not contribute to current are responsible for generating heat which reduces device performance. Hence, for improved performance it becomes desirable to design PV devices to maximize absorbance within the active layer while maximizing reflectance elsewhere. We have simulated copper indium gallium diselenide (CIGS) based PV consisting of various single layered antireflection coatings (ARC) including MgF2, Al2O3, SiO2, and TiO2 and evaluated their effectiveness in performance enhancements in the air mass (AM) 0 and 1.5G corresponding to space and terrestrial applications. Optical simulations are performed in the wavelength range from 300 - 2500 nm to determine absorbance in the CIGS active layer which is equated to external quantum efficiency spectra and reflected power of the complete PV device above and below the CIGS bandgap to assess relative heating with the different ARCs.  MgF2 provided the most effective ARC as assessed from current generation, however TiO2 exhibited the highest infrared range reflected power. The methodology can be applied to other single and multijunction PV devices to further optimize performance.