Zhang Qi, Yu Haomiao, Pei Liying, Li Jinpeng, Wang Kai, Zhang Jia, Wang Miaosheng, Hu Bin
Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044, China.
Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States.
J Phys Chem Lett. 2020 Dec 17;11(24):10323-10328. doi: 10.1021/acs.jpclett.0c02934. Epub 2020 Nov 23.
In hybrid metal halide perovskites, electrons carry both orbital and spin momenta through s-p wave function hybridization. This leads to a hypothesis that the orbit-orbit interaction between excitons can occur through orbital magnetic dipoles forming short-range interaction or through orbital polarizations forming long-range interaction to influence optoelectronic properties. This Letter reports an interesting phenomenon: the orbit-orbit interaction can be electrically switched between orbital magnetic dipoles and orbital polarizations in a flexible perovskite (MAPbICl) solar cell by scanning an external voltage between forward and reverse biases (0.2 and -0.2 V). Essentially, this phenomenon presents an external mechanism for electrically controlling the internal orbit-orbit interaction in hybrid perovskites. It was further observed that this bias-switchable orbit-orbit interaction is sensitive to temperature, becoming negligible when the temperature is decreased from 300 to 250 K. This observation indicates that the mobile ions driven by an external electrical field provide an intrinsic mechanism for electrically switching the orbit-orbit interaction through polarization and spin parameters while applying an external voltage between forward and reverse biases. These results provide a comprehensive understanding of tuning the orbit-orbit interaction in flexible perovskites toward developing orbitronic actions.
在混合金属卤化物钙钛矿中，电子通过s-p波函数杂化携带轨道动量和自旋动量。这引发了一个假设，即激子之间的轨道-轨道相互作用可以通过形成短程相互作用的轨道磁偶极子或通过形成长程相互作用的轨道极化来发生，从而影响光电特性。本信函报道了一个有趣的现象：通过在正向和反向偏置（0.2和-0.2 V）之间扫描外部电压，在柔性钙钛矿（MAPbICl）太阳能电池中，轨道-轨道相互作用可以在轨道磁偶极子和轨道极化之间进行电切换。从本质上讲，这一现象为电控制混合钙钛矿中的内部轨道-轨道相互作用提供了一种外部机制。进一步观察到，这种偏置可切换的轨道-轨道相互作用对温度敏感，当温度从300 K降至250 K时，这种相互作用变得可以忽略不计。这一观察结果表明，在正向和反向偏置之间施加外部电压时，由外部电场驱动的移动离子通过极化和自旋参数提供了一种电切换轨道-轨道相互作用的内在机制。这些结果为在柔性钙钛矿中调节轨道-轨道相互作用以发展轨道电子学行为提供了全面的理解。
