Lu Haipeng, Carroll Gerard M, Chen Xihan, Amarasinghe Dinesh K, Neale Nathan R, Miller Elisa M, Sercel Peter C, Rabuffetti Federico A, Efros Alexander L, Beard Matthew C
Chemistry & Nanoscience Center , National Renewable Energy Laboratory , Golden , Colorado 80401 , United States.
Department of Chemistry , Wayne State University , Detroit , Michigan 48202 , United States.
J Am Chem Soc. 2018 Oct 24;140(42):13753-13763. doi: 10.1021/jacs.8b07910. Epub 2018 Oct 9.
We developed a postsynthetic treatment to produce impurity n-type doped PbSe QDs with In as the substitutional dopant. Increasing the incorporated In content is accompanied by a gradual bleaching of the interband first-exciton transition and concurrently the appearance of a size-dependent, intraband absorption, suggesting the controlled introduction of delocalized electrons into the QD band edge states under equilibrium conditions. We compare the optical properties of our In-doped PbSe QDs to cobaltocene treated QDs, where the n-type dopant arises from remote reduction of the PbSe QDs and observe similar behavior. Spectroelectrochemical measurements also demonstrate characteristic n-type signatures, including both an induced absorption within the electrochemical bandgap and a shift of the Fermi-level toward the conduction band. Finally, we demonstrate that the In dopants can be reversibly removed from the PbSe QDs, whereupon the first exciton bleach is recovered. Our results demonstrate that PbSe QDs can be controllably n-type doped via impurity aliovalent substitutional doping.
我们开发了一种合成后处理方法，以制备以铟作为替代掺杂剂的杂质n型掺杂PbSe量子点。随着掺入铟含量的增加，带间第一激子跃迁逐渐发生漂白，同时出现尺寸依赖性的带内吸收，这表明在平衡条件下，可控制地将离域电子引入量子点的带边态。我们将掺铟PbSe量子点的光学性质与经二茂钴处理的量子点进行比较，后者的n型掺杂源自PbSe量子点的远程还原，并且观察到了类似的行为。光谱电化学测量也证明了特征性的n型特征，包括电化学带隙内的诱导吸收以及费米能级向导带的移动。最后，我们证明铟掺杂剂可以从PbSe量子点中可逆地去除，随后第一激子漂白得以恢复。我们的结果表明，PbSe量子点可通过杂质异价替代掺杂实现可控的n型掺杂。
