Giant Bandgap Renormalization and Exciton-Phonon Scattering in Perovskite Nanocrystals
Giant Bandgap Renormalization and Exciton-Phonon Scattering in Perovskite Nanocrystals
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DOI：
10.1002/adom.201700231
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发表时间：
2017-09-01
影响因子：
9
通讯作者：
Curry, Richard J.
中科院分区：
文献类型：
--
作者：
Saran, Rinku;Heuer-Jungemann, Amelie;Curry, Richard J.
了解光激发荷载载流子（电子和孔）与量子振动（声子）之间的相互作用是量子限制的半导体纳米晶体（NCS）之间的相互作用，这是基本的兴趣，也是其用于制造高强度光电设备的先决条件。这种相互作用对其光电特性（包括其电荷载体迁移率和光致发光）具有重大影响。在这里，这些相互作用在瓶中铅卤化物（CSPBX3，X是Cl，Br或I）NC Perovskites中进行了研究。结果表明，这些NC中的激子线宽的广泛扩展是由强烈的激子 - phonon耦合引起的，该耦合基本上由纵向光学声子通过Frhlich的相互作用主导。与常规半导体的行为不同，这些NCS通常以降低温度显示其发射能峰的一般红移。有趣的是，CSPBCL3 NCS还显示了初始的蓝光，并在结构相转变时大约在175-200 K处进行。对观察到的异常红移进行了建模和分析，并使用Bose-Einstein Trix-oscillator模型来解释具有抗激元与声音和声学和声音和声音和声音和声音和声音的相互作用的模型诱导带隙重新归一化的光学声子。由于零点运动（T = 0 K）引起的净重新归化分别约为41.6，而CSPBBR3和CSPBI3 NCS分别约为94.9 MeV。
Understanding the interactions between photoexcited charge carriers (electrons and holes) with lattice vibrations (phonons) in quantum confined semiconductor nanocrystals (NCs) is of fundamental interest and a prerequisite for their use in fabricating high-performance optoelectronic devices. Such interactions have a significant impact on their optoelectronic properties including their charge carrier mobility and photoluminescence. Here, these interactions are investigated in cesium lead halide (CsPbX3, where X is Cl, Br, or I) NC perovskites. It is shown that a wide broadening of the excitonic linewidth in these NCs arises from strong exciton-phonon coupling, which is substantially dominated by longitudinal optical phonons via the Frhlich interaction. Unlike the behavior of conventional semiconductors these NCs display a general redshift of their emission energy peak with reducing temperature. Interestingly, the CsPbCl3 NCs also display an initial blueshift and undergo at structural phase transition at approximate to 175-200 K. The anomalous redshift observed is modeled and analyzed using a Bose-Einstein two-oscillator model to interpret the interaction of excitons with acoustic and optical phonons which induce a renormalization of the bandgap. The net renormalization due to zero point motion (T = 0 K) is found to be approximate to 41.6 and approximate to 94.9 meV for CsPbBr3 and CsPbI3 NCs, respectively.