论文标题
直接证据表明弱分散和强烈的静脉光子声子在混合钙钛矿中
Direct evidence of weakly dispersed and strongly anharmonic optical phonons in hybrid perovskites
论文作者
论文摘要
混合有机层钙钛矿（HOP）已经开始在光伏领域中建立自己的位置，这主要是由于它们的巨大光电特性并稳步提高了太阳能电池效率。对晶格动力学的研究是理解造成这种特性的电子 - phonon相互作用的关键。在这里，我们通过中子和拉曼光谱镜调查了四个不同的单晶晶体的光学声子光谱：mapbbr $ _3 $，fapbbr $ _3 $，mapbi $ _3 $和$α$ -fapbi $ _3 $。低温光谱显示出低至2-5〜MEV的能量弱分散的光学声子，这似乎是这些材料中电荷载体迁移率极限的起源。我们的中子光谱的温度依赖性也显示出一种显着的非谐调行为，导致在低至80〜K的温度下失水，从而询问了在太阳能电池运行的室温下，准粒子图片的有效性低。
Hybrid organolead perovskites (HOP) have started to establish themselves in the field of photovoltaics, mainly due to their great optoelectronic properties and steadily improving solar cell efficiency. Study of the lattice dynamics is key in understanding the electron-phonon interactions at play, responsible for such properties. Here, we investigate, via neutron and Raman spectroscopies, the optical phonon spectrum of four different HOP single crystals: MAPbBr$_3$, FAPbBr$_3$, MAPbI$_3$, and $α$-FAPbI$_3$. Low temperature spectra reveal weakly dispersive optical phonons, at energies as low as 2-5~meV, which seem to be the origin of the limit of the charge carriers mobilities in these materials. The temperature dependence of our neutron spectra shows as well a significant anharmonic behaviour, resulting in optical phonon overdamping at temperatures as low as 80~K, questionning the validity of the quasi-particle picture for the low energy optical modes at room temperature where the solar cells operate.
