Optical and Electrical Characterization of High-Efficiency InGaP/InGaAs/Ge Triple-Junction Solar Cell Incorporated with InGaAs/GaAs QDs Layers in Middle cell

摘要

In this study, the MOCVD grown InGaP/InGaAs/Ge triple-junction (3-J) solar cell incorporated with the InGaAs/GaAs quantum dots (QDs) layers in the middle cell to achieve 33.5% conversion efficiency (η) under one-sun AM1.5 G illumination is demonstrated. Optical reflective spectrum, dark and photo current-voltage (Ⅰ-Ⅴ) characteristics, external quantum efficiency (EQE) response, and capacitance as a function of frequency under dark and illuminated conditions were measured and characterized. With 50 layers of In_(0.7)Ga_(0.3)As (QD)/GaAs (Barrier) QDs-structure, an impressive EQE enhancement of 35% at 900-930 nm was observed in the middle cell. Thus, the short-circuit current-density (J_(SC)) of 15.43 mA/cm~2, open-circuit voltage (V_(OC)) of 2.54 V, fill factor (FF) of 84.7%, and η = 33.5% were obtained as the cell with the QDs layer. In addition, the capacitance dependence of frequency result shows that using 50 pairs In_(0.7)Ga_(0.3)As/GaAs QD-structure in the middle cell exhibited a strain-balanced high quality epitaxy film and extended the spectral bandwidth of the middle cell.