A study on the influence of the albedo spectrum on the bifacial GaAs/c-Si heterojunction tandem solar cell using computer modelling

摘要

Recently, III-V/c-Si heterojunction (c-Si HJ) tandem solar cells received considerable attention owing to their high conversion efficiency. In a tandem configuration, current matching has a significant impact on conversion efficiency. Specifically, in the two-terminal tandem structure, the sub-cell with the lowest current density (J(sc)) dominates the J(sc) of the tandem cell, which in turn, dominates the overall conversion efficiency of the tandem device. Meanwhile, in a four-terminal tandem structure, although the current matching condition is not mandatory, an efficient light distribution is necessary to achieve high efficiency in each sub-cell, which in turn results in a high efficiency of the tandem cell. Herein, we propose two- and four-terminal GaAs/c-Si HJ tandem solar cells using effective albedo reflections (R-A) to overcome the aforementioned limitations. As R-A increased, the current density of the c-Si HJ solar cells increased from 3.07 mA/cm(2) (R-A =10%) to 39.90 mA/cm(2) (R-A =100%) on the rear side of the cell, thereby, overcaming the existing current density limit. In addition, we investigated the tandem structures via simulation to provide a practical direction for achieving high efficiency. Finally, normalised outputs of 40.00% and 40.31% were achieved for the two-terminal and four-terminal GaAs/c-Si HJ bifacial tandem solar cells, respectively, with a real-life albedo from common ground surfaces, such as sand.