Selective rear contact for Ga0.5In0.5P- and GaAs- based solar cells

The light management strategy was applied in III-V solar cells for the maximum utilization of incident photon, namely the selective rear contact was adopted in Ga0.5In0.5P- and GaAs- based solar cells. By etching the rear contact layer (p-GaAs) with photolithography, the distinctive morphological structures consisting of polka-dot patterns were formed, which led to increased reflection and thereby the device performance. Furthermore, the photolithography was controlled to find the optimum contact ratio between the back-surface field and the rear contact. Consequently, the conversion efficiency was increased from η = 15.5% to 16.3% for the Ga0.5In0.5P-based single-junction solar cell, and from η = 21.1% to 21.9% for the GaAs-based one, both at the contact ratio of 10%, compared to the cells with full (100%) rear contact ratio. Finally, the selective rear contact was applied to double-junction solar cells (Ga0.5In0.5P- and GaAs- based), exhibiting that this straightforward rear-contact strategy has enabled reaching the efficiency of η = 30.6% with an anti-reflective coating.