Functionalized Rare-Earth Metal Cluster-Based Materials as Additives for Enhancing the Efficiency of Perovskite Solar Cells

The polynuclear metal-organic frameworks (MOFs) possess satisfactory chemical and thermal stability and exhibit promising potential as candidates for improving the working performance of photoelectric devices. Herein, two polynuclear rare-earth MOFs, Tb-TZB and Tb-FTZB, (H2TZB = 4-(1H-tetrazol-5-yl) benzoic acid, H2FTZB = 2-fluoro-4-(1H- tetrazol-5-yl) benzoic acid) with a face-centered cubic (fcu) topology are synthesized through the solvothermal method. The highly chemically stable framework and matched energy levels make them ideal additives for the hole transport layer to optimize perovskite solar cells (PSCs). The N and O elements containing lone-pair electrons in the MOF framework interact with uncoordinated Pb2+ and passivate the surface defects of the perovskite film, thus promoting carrier transport in the interface and enhancing the power conversion efficiency (PCE) of the two MOF-modified PSCs. Specifically, the PCE of Tb-FTZB-modified PSCs increases to 21.31% with remarkable repeatability and good stability under long-time storage, indicating the reliability of the fluorine substitution strategy. This work suggests an efficient route to realize high-performance PSCs by employing structurally stable MOF additives.