By changing the precursor lead‐to‐sulfur molar ratio in the synthesis of colloidal PbS nanosheets, the lateral size of the nanosheet can be tuned in a wide range from 100 nm to 1500 nm while keeping its thickness around 2.4 nm. Using chloroalkane molecules with a long carbon‐chain as the capping ligands can further reduce the lateral size down to 20 nm. The concentration of the chloroalkane in the reaction solution and the reaction temperature also have significant effects on the lateral size. At room temperature, nanosheets with a small lateral size exhibit a narrow light‐emission linewidth. The same nanosheets also show a sharp exciton peak near the band edge in the optical absorption spectrum.

中文翻译：

---

控制胶体PbS纳米片的横向尺寸和激子性质

通过在胶体PbS纳米片的合成中更改前体铅与硫的摩尔比，可以在100 nm至1500 nm的宽范围内调整纳米片的横向尺寸，同时将其厚度保持在2.4 nm左右。使用具有长碳链的氯代烷烃分子作为封端配体可以进一步将横向尺寸减小至20 nm。反应溶液中氯烷烃的浓度和反应温度也对侧向尺寸有显着影响。在室温下，横向尺寸较小的纳米片的发光线宽较窄。相同的纳米片在光吸收光谱中的能带边缘附近也显示出尖锐的激子峰。