High-Performance Monolithic Perovskite/Organic Tandem Solar Cells

The emergence of solution-processed organic and metal halide perovskite solar cells can transform the landscape of photovoltaic technology in delivering scalable and high-performance solar cells to provide sustainable green energy. While the power conversion efficiencies (PCEs) of both single-junction organic solar cells (OSCs) and perovskite solar cells (PSCs) are rapidly ascending to &gt;19% and &gt;25%, respectively, their maximum efficiency is limited to ~33% accordingly to the Shockley-Queisser model for single-junction devices. However, it is possible to significantly increase the efficiency of solar cells by constructing a tandem device that consists of multiple light absorbers with considerably different bandgaps to reduce the solar cells' overall transmission and thermalization losses.<br/>In this talk, I will discuss our work on developing high performance monolithic perovskite/organic tandem solar cells comprising a wide bandgap perovskite (WBG) front cell and a narrow bandgap (NBG) organic rear cell connected through a recombination junction. The WBG (Eg: 1.7-1.85 eV) PSCs are chosen for the front cell due to their strong and broad absorption for visible light, smaller voltage loss, and higher photoresponse compared to their organic counterparts with approximate bandgap. While NBG (Eg: 1.1-1.25 eV) OSCs can offer better near-infrared absorption tunability and stability compared with the Sn-based NBG perovskites, making them favorable candidates for the rear cell.^[1] Moreover, the advantage of the perovskite and organic light absorbing layers being processed from orthogonal solvents imposes fewer constraints on the choice of the materials for constructing the recombination junction and provides better flexibility on the device design of tandem solar cells.<br/>To demonstrate state-of-the-art perovskite/organic tandem cells, an integrated strategy combining materials, interface, optical, and process engineering was adopted to optimize the two subcells and the interconnect junction simultaneously.^[2-5]In addition, a comprehensive optoelectronic model is being developed to simulate the electrical and optical properties of the tandem solar cells and to provide guidelines to optimize their device performance. The successful development of perovskite/organic tandem cells will have far-reaching impacts on producing high efficiency, low cost and scalable PV cells for clean energy production.<br/><br/>Reference:<br/>[1] Yip, H.-L. et al, Renewed Prospects for Organic Photovoltaics. <i>Chemical Reviews</i> 2022, 122, 95<br/>[2] Yip, H.-L. et al, Homogeneous grain boundary passivation in wide bandgap perovskite films enables fabrication of monolithic perovskite/organic tandem solar cells with over 21% efficiency. <i>Advanced Functional Materials</i> 2022, <i>32</i>, 2112126.<br/>[3] Yip H.-L. et al, Dual Sub Cells Modification Enables High Efficiency n–i–p Type Monolithic Perovskite/Organic Tandem Solar Cells. <i>Advanced Functional Materials</i> 2023, <i>33</i>, 2212599.<br/>[4] Yip, H.-L et al, All-Inorganic Perovskite-Based Monolithic Perovskite/Organic Tandem Solar Cells with 23.21% Efficiency by Dual-Interface Engineering. <i>Advanced Energy Materials</i>, 2023, 13, 2204347.<br/>[5] Yip, H.-L et al, Optimizing Crystallization in Wide Bandgap Mixed Halide Perovskites for High Efficiency Solar Cells. <i>Advanced Materials</i> 2023, 35, 2306568