Lead sulfide (PbS) quantum dots are promising solution-processed materials for short-wave infrared (SWIR) photodetectors due to their tunable band gap and solution processability. Phase-transfer ligand exchange is a common method to prepare quantum dot (QD) inks used in device fabrication. For large-sized PbS QDs used for SWIR detection, the conventional phase-transfer ligand exchange has been problematic due to the densely packed organic ligands and charge-neutral (100) facets. Here, we report a new strategy to carry out the efficient phase-transfer ligand exchange in large-sized QDs. Specifically, using lead acetate trihydrate (PbAc₂·3H₂O) as a precursor and methylammonium acetate (MAAc) as an additive in the ligand solution, we can facilitate the efficient phase-transfer ligand exchange and epitaxial growth of perovskite intermediate (MAPbI_3–xAc_x) on the (100) facets, resulting in a significant improvement in film quality suitable for device fabrication. The resulting photodiodes show a 2.5× enhancement in external quantum efficiency (EQE) compared to devices using QD inks obtained using the conventional method. Considering the low transmittance of the ITO electrode in the SWIR regime, our devices exhibit an internal quantum efficiency of over 90%.

中文翻译：

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用于短波长光电探测器的硫化铅量子点的增强表面钝化

硫化铅 (PbS) 量子点是用于短波红外 (SWIR) 光电探测器的有前途的溶液处理材料，因为它们具有可调节的带隙和溶液可加工性。相转移配体交换是制备用于器件制造的量子点 (QD) 墨水的常用方法。对于用于 SWIR 检测的大尺寸 PbS QD，由于有机配体和电荷中性 (100) 晶面的密集排列，传统的相转移配体交换一直存在问题。在这里，我们报告了一种在大型量子点中进行有效相转移配体交换的新策略。具体来说，使用醋酸铅三水合物（PbAc ₂ ·3H ₂O）作为前体和乙酸甲基铵（MAAc）作为配体溶液中的添加剂，我们可以促进钙钛矿中间体（MAPbI _{3– x} Ac _x）在（100）面上的有效相转移配体交换和外延生长，导致适用于器件制造的薄膜质量显着提高。与使用传统方法获得的 QD 墨水的器件相比，所得光电二极管的外量子效率 (EQE) 提高了 2.5 倍。考虑到 ITO 电极在 SWIR 区域的低透射率，我们的器件表现出超过 90% 的内量子效率。