Interplay of Structure, Charge-Carrier Localization and Dynamics in Copper-Silver-Bismuth-Halide Semiconductors
Interplay of Structure, Charge-Carrier Localization and Dynamics in Copper-Silver-Bismuth-Halide Semiconductors
复制标题
DOI：
10.1002/adfm.202108392
复制
发表时间：
2021-10-27
影响因子：
19
通讯作者：
Herz, Laura M.
中科院分区：
文献类型：
--
作者：
Buizza, Leonardo R., V;Sansom, Harry C.;Herz, Laura M.
银铋基半导体由于其高稳定性、全无机组成和有利的光电性能而代表了一类有前途的新型光电应用材料。在这项研究中，电荷载流子动力学和输运性质的研究跨越五个组成沿着AgBiI 4-CuI固溶体线（化学计量Cu-4 x（AgBi）（1-x）I-4）。发现密堆积的碘化物亚晶格的存在为所有这些材料的一般半导体性质提供了良好的骨架，发现其光电性质随着铜含量的增加而显著改善，这增强了光致发光强度和电荷载流子输运。光致发光和光激发能量依赖的太赫兹光电导测量表明，这种增强的电荷载流子传输来自减少的阳离子无序和改善的电子连接，由于Cu+的存在。此外，增加的Cu+含量增强了价带最大值周围的能带曲率，导致较低的电荷载流子有效质量、降低的激子结合能和较高的迁移率。最后，超快的电荷载流子本地化的脉冲光激发后，观察到在所有的组合物调查，降低电荷载流子的迁移率，并导致Langevin样的双分子复合。这个过程的结论是内在联系的存在下的银和铋，和策略，以定制或减轻效果的建议和讨论。
Silver-bismuth based semiconductors represent a promising new class of materials for optoelectronic applications because of their high stability, all-inorganic composition, and advantageous optoelectronic properties. In this study, charge-carrier dynamics and transport properties are investigated across five compositions along the AgBiI4-CuI solid solution line (stoichiometry Cu-4x(AgBi)(1-x)I-4). The presence of a close-packed iodide sublattice is found to provide a good backbone for general semiconducting properties across all of these materials, whose optoelectronic properties are found to improve markedly with increasing copper content, which enhances photoluminescence intensity and charge-carrier transport. Photoluminescence and photoexcitation-energy-dependent terahertz photoconductivity measurements reveal that this enhanced charge-carrier transport derives from reduced cation disorder and improved electronic connectivity owing to the presence of Cu+. Further, increased Cu+ content enhances the band curvature around the valence band maximum, resulting in lower charge-carrier effective masses, reduced exciton binding energies, and higher mobilities. Finally, ultrafast charge-carrier localization is observed upon pulsed photoexcitation across all compositions investigated, lowering the charge-carrier mobility and leading to Langevin-like bimolecular recombination. This process is concluded to be intrinsically linked to the presence of silver and bismuth, and strategies to tailor or mitigate the effect are proposed and discussed.