Phase segregation due to ion migration in all-inorganic mixed-halide perovskite nanocrystals
Phase segregation due to ion migration in all-inorganic mixed-halide perovskite nanocrystals
复制标题
全无机混合卤化物钙钛矿纳米晶体中离子迁移导致的相分离
DOI：
10.1038/s41467-019-09047-7
复制
发表时间：
2019-03-06
影响因子：
16.6
通讯作者：
Xiao, Min
中科院分区：
文献类型：
--
作者：
Zhang, Huichao;Fu, Xu;Xiao, Min
半导体混合卤化物钙钛矿具有可调的能带隙，是叠层太阳能电池中光吸收剂以及发光二极管和纳米激光器中荧光材料的理想候选者。这些器件的进步目前受到光致相分离效应的阻碍，由此离子迁移将产生具有红移光致发光的较小带隙域。在这里，我们表明，在激光激发所有无机混合卤化物纳米晶体意外地表现出蓝移的光致发光峰，可以恢复在黑暗中，从而描绘了离子迁移的过程中，并返回到最初激发的纳米晶体。有趣的是，这种可逆的光致发光位移也可以通过混合卤化物纳米晶体的电偏置而不注入电荷载流子来诱导。上述发现表明，正是局部电场破坏了混合卤化物纳米晶体中的离子键，这可能是在其他混合卤化物钙钛矿材料中观察到的光致相分离的普遍起源。
Semiconductor mixed-halide perovskites featured with a tunable energy bandgap are ideal candidates for light absorbers in tandem solar cells as well as fluorescent materials in light-emitting diodes and nanoscale lasers. These device advancements are currently hindered by the light-induced phase segregation effect, whereby ion migration would yield smaller-bandgap domains with red-shifted photoluminescence. Here we show that upon laser excitation all-inorganic mixed-halide nanocrystals unexpectedly exhibit a blue shift in the photoluminescence peak that can revert back in the dark, thus depicting the processes of ion migration out of and back to the originally excited nanocrystals. Interestingly, this reversible photoluminescence shift can also be induced by electrical biasing of mixed-halide nanocrystals without the injection of charge carriers. The above findings suggest that it is the local electric field that breaks the ionic bonds in mixed-halide nanocrystals, which could be a universal origin for light-induced phase segregation observed in other mixed-halide perovskite materials.