SPLTRAK Abstract Submission
Current or power matching? A third option for monolithic all-perovskite tandem solar cells
Yuan Gao1, Renxing Lin2, Ke Xiao2, Xin Luo2, Jin Wen2, Xu Yue3, Hairen Tan2
1Lawrence Berkeley National Laboratory, Berkeley, CA, United States
/2National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing, China
/3Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Sci, Nanjing, China

Multijunction solar cells offer high potential to improve the efficiency beyond the single-junction limit. The record power conversion efficiency of monolithic all-perovskite tandem solar cells (26.4%) has now surpassed that of the single-junction counterparts (25.7%). The two-terminal tandem architectures, in most cases, require a “matched” current between the top and bottom subcells for an optimal tandem performance. In some cases, where the two subcells have distinct fill factors, a “power matching” strategy shows better performance than “current matching”. In this study, we prove that optimal performance of monolithic all-perovskite tandem solar cells is obtained when the top subcell has a higher short-circuit current than the bottom one. This is attributed to both optical and electrical properties of the all-perovskite tandem cells. We also investigate the optimal tandem configurations under real-world conditions, where solar spectra, angle of incidence, and cell temperature are different from the standard test conditions. We find that the top subcell shifts to thinner optimal thickness under blue-rich solar spectra. We also observe that the bottom subcell shifts to thicker optimal thickness due to larger angle of incidence under real-world conditions. Since two perovskite subcells have similar temperature coefficients, the real-world cell temperatures have little impact the optimal tandem configurations, but will affect the annual energy yield. We further obtain the real-world optimized tandem configurations, which can increase the annual energy yield compared with the one optimized under standard test conditions. The current-mismatching losses under real-world conditions can be reduced by optimized configurations, and even be turned into energy gains in certain cases. This finding enhances the confidence in promoting high-efficient, customizable tandem solar cells for different regions and installation methods.