Structural tunability and switchable exciton emission in inorganic-organic hybrids with mixed halides
Structural tunability and switchable exciton emission in inorganic-organic hybrids with mixed halides
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DOI：
10.1063/1.4851715
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发表时间：
2013-12-21
影响因子：
3.2
通讯作者：
Prakash, G. Vijaya
中科院分区：
文献类型：
--
作者：
Ahmad, Shahab;Baumberg, Jeremy J.;Prakash, G. Vijaya
室温可调谐激子光致发光表现在合金调谐的层状无机-有机（IO）杂化物（C12 H25 NH3）（2）PbI 4（1-y）Br 4 y（y = 0到1）中。这些钙钛矿IO混合物采用具有低维无机层和有机层的交替堆叠的结构，被认为是自然自组装的多量子威尔斯。这些系统类似于堆叠的单层2D半导体，因为不存在层间耦合。由于低维无机层内形成的稳定激子，IO杂化薄膜在室温下表现出尖锐而强烈的光致发光（PL）。在所观察到的激子PL从510 nm到350 nm的合金组合物的变化，系统的变化，是由于晶体包装的结构调整后，在Pb-I无机网络中的Br含量的增加。激子吸收和PL之间的能量分离归因于修改的激子态密度和激子从对应于富溴位点的相对较高能量状态向较低能量碘位点的扩散。除了成分波动，这些激子显示出显着的可逆翻转温度诱导的相变。所有的结果都成功地与热和结构的研究。这些混合物中的这种结构工程灵活性允许在合适的操作温度范围内选择性地调节期望的激子性质。这种宽范围的PL可调谐性和可逆的激子开关在这些新的IO混合铺平了道路，在新一代的光电器件的潜在应用。(C)2013 AIP Publishing LLC.
Room-temperature tunable excitonic photoluminescence is demonstrated in alloy-tuned layered Inorganic-Organic (IO) hybrids, (C12H25NH3)(2)PbI4(1-y)Br4y (y = 0 to 1). These perovskite IO hybrids adopt structures with alternating stacks of low-dimensional inorganic and organic layers, considered to be naturally self-assembled multiple quantum wells. These systems resemble stacked monolayer 2D semiconductors since no interlayer coupling exists. Thin films of IO hybrids exhibit sharp and strong photoluminescence (PL) at room-temperature due to stable excitons formed within the low-dimensional inorganic layers. Systematic variation in the observed exciton PL from 510 nm to 350 nm as the alloy composition is changed, is attributed to the structural readjustment of crystal packing upon increase of the Br content in the Pb-I inorganic network. The energy separation between exciton absorption and PL is attributed to the modified exciton density of states and diffusion of excitons from relatively higher energy states corresponding to bromine rich sites towards the lower energy iodine sites. Apart from compositional fluctuations, these excitons show remarkable reversible flips at temperature-induced phase transitions. All the results are successfully correlated with thermal and structural studies. Such structural engineering flexibility in these hybrids allows selective tuning of desirable exciton properties within suitable operating temperature ranges. Such wide-range PL tunability and reversible exciton switching in these novel IO hybrids paves the way to potential applications in new generation of optoelectronic devices. (C) 2013 AIP Publishing LLC.