Perovskite/c‐Si tandem solar cells with realistic inverted architecture: Achieving high efficiency by optical optimization

• Published in: Progress in photovoltaics Vol. 26; no. 11; pp. 924 - 933
• Main Authors: Ba, Lixiang, Liu, Hong, Shen, Wenzhong
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.11.2018
• Subjects: Architecture; Current loss; Efficiency; FDTD; Finite difference time domain method; inverted configuration; light path analysis; optical and electrical optimization; Optimization; perovskite/c‐Si monolithic TSCs; Perovskites; Photovoltaic cells; Pyramids; Solar cells; Time domain analysis
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.3037

Many theoretical analyses for perovskite/c‐Si monolithic tandem solar cells (TSCs) have shown optical optimization and high efficiency limits, but they use many idealized assumptions and draw some unpractical conclusions for experiments. In this work, we have introduced a composite method combining the finite difference time domain and light path analysis for the first time. By using this method, we have systematically calculated perovskite/c‐Si monolithic TSCs with inverted architecture based on realistic solar cell parameters. Theoretical results have demonstrated very good match of the experimental external quantum efficiencies of both subcells. More importantly, from optical and electrical point of view, we have analyzed current losses of such TSCs and proposed detailed optimization for achieving high efficiency. Finally, we have presented improved configuration of perovskite/c‐Si monolithic TSCs with addition of pyramids structure in front surface, which can effectively increase the tandem cell efficiency to 29.05%. This work can be served as a practical guidance for the realization of high‐efficient perovskite/c‐Si monolithic TSCs. We have found that the current loss in parasitic absorption of top ITO and cell surface reflection can be reduced from 2.1 and 6.8 mA/cm2 to 1.7 and 2.5 mA/cm2, respectively, by using the optimized carrier density of top ITO (5 × 1019 cm−3) and sizes of pyramids (Ptop~1 μm). The best calculated efficiency of 29% is achieved at 1.76‐eV perovskite bandgap and FA0.85Cs0.15Pb(Br0.4I0.6)3 material. These results will provide useful guidelines for the realization of high‐efficient perovskite/c‐Si monolithic tandem solar cells.