Improving Performance of Bifacial-Grid III-V Solar Cells Bonded on Glass by Selective Contact Annealing

Selective contact annealing is developed to improve the performance of bifacial-grid III-V top cells bonded on glass by epoxy resin for Si-based tandem solar cells. The annealing method can minimize the damage to the bonding layer and is compatible with the industrial evaporation technique for contact fabrication. The improvement of the front contact quality by selective annealing treatments is demonstrated through optical and electrical characterization which shows a significantly enhanced III-V device performance. Furthermore, a fitting model is established to reveal the mechanism underlying the performance improvement through the reduction of contact resistances and the bad contact area. Herein, an effective annealing approach to fabricate high-quality metal-semiconductor contacts for devices with poor thermal resistivity is demonstrated, which can be used in polymer-bonded top cells in Si-based tandem solar cells and other flexible optoelectronic devices on polymer substrates.