Broadband Graded Refractive Index TiO2/Al2O3/MgF2 Multilayer Antireflection Coating for High Efficiency Multi-Junction Solar Cell

The effects of TiO2/Al2O3/MgF2 triple-layer (TL) antireflection (AR) coating on reducing optical loss of GaInP/InGaAs/Ge triple-junction (TJ) solar cell have been investigated by using Essential Macleod Program software and Crosslight Apsys software, and compared to that of TiO2/Al2O3 dual-layer (DL) AR coating. The DLAR and TLAR coatings have reduced the average optical reflectivity values of the TJ solar cells by around 18.9% and 22.2%, respectively. The conversion efficiency of TJ solar cell was increased by 21.29% and 29.44% with DLAR and TLAR coatings. External quantum efficiency values of TJ solar cells with DL and TLAR coating increased in full wavelength region due to the increase of photo generated current density caused by the reduction of surface reflectivity. Both simulation and experimental results showed that the TiO2/Al2O3/MgF2 TLAR coating has better anti-reflecting properties over TiO2/Al2O3 DLAR coating, and improved the overall performance of TJ solar cell more.