Impact of MAI-ligand-passivated PbS quantum dot concentration on the photovoltaic performance of PbS/MAPbI3 core-shell nanorod array solar cells

Enhancing the power conversion efficiency of solar cells requires effective utilization of the full solar spectrum. In this work, we develop PbS/MAPbI 3 core-shell nanorod arrays that integrate the light-trapping and directional charge-transport benefits of nanorod architectures with the strong visible-light absorption of perovskites and the near-infrared response of PbS quantum dots (QDs). A key challenge lies in mitigating heterointerface defects, which we address by passivating the PbS QD surface with methylammonium iodide (MAI)—a strategy that simultaneously reduces surface defects and modulates perovskite crystallization. We identify the concentration of MAI-passivated PbS QDs as a critical parameter governing interfacial morphology, which in turn determines perovskite film quality, defect density, and charge dynamics. Systematic optimization over a concentration range of 40-100 mg/mL reveals that a concentration of 60 mg/mL yields a uniform and continuous QD interlayer. This optimal interlayer promotes high-quality MAPbI 3 growth, reduces defect density, and effectively suppresses non-radiative recombination—as confirmed by the minimized Urbach energy (0.102 eV) and maximized recombination resistance (20646 Ω). The champion device achieves a power conversion efficiency of 9.09%, with concurrent enhancements in open-circuit voltage and fill factor. Collectively, these results establish a clear relationship between processing conditions, interfacial structure, and device performance in core-shell nanorod solar cells, while elucidating how QD layer morphology governs perovskite crystallization and interfacial carrier dynamics.