钙钛矿微腔中光子与激子强耦合作用研究

Exciton polartion is a kind of hybrid quasi-particles coupled with photons and excitons. It has many unique phenomena, such as polariton condensates and polariton laser at high temperature, superfluid and optical limiter. This excellent characteristics can be beneficial for low threshold lasing and the development of optical-logic elements. The robust excitons and high quality micro cavities are ultra-needed for practical polariton applications. In recent years, perovskites have gained attention in strong light–matter coupling due to their large exciton binding energy and oscillator strength. In this project, we use perovskite based microcavities as the target to study the origin and related properties of exciton–polaritons. The project is started by the fabrication of perovskite microcavities by means of chemical vapor deposition and material transferring, followed with angle- resolved spectroscopy and multi–light sources excitation in order to study the polariton mode distribution, the origin of polariton laser and the transmission of polariton. In the end, we use pump-probe spectroscopy to study the dynamics of generation and relaxation of exciton–polaritons and investigate the role of polariton in the optoelectronic properties of semiconductor devices.

激子极化激元是一种光与激子杂化的准粒子。它具有一系列独特的性质，如高温下极化子凝聚和极化子激光，超流现象和光限幅效应等。这些性质有利于实现低阈值激光和光逻辑器件。构建实用的极化子器件需要稳定的激子，高质量的微腔结构等。钙钛矿近年来由于其较高的激子束缚能和振子强度在光与物质强耦合方面的研究引起人们的关注。本项目将钙钛矿微腔作为研究对象，研究其激子极化激元的产生和相关的性质。首先通过化学气相沉积和样品转移得到钙钛矿光学微腔。随后，利用角分辨荧光和吸收光谱研究其极化子模式分布和极化子激光的产生；同时利用多光束系统研究光调控微腔中极化子的传输机制。最后，运用泵浦-探测光谱技术研究极化子的产生、弛豫的动力学过程，探讨极化子对光电器件性能的影响。

钙钛矿材料在低阈值激光器、光电探测、太阳能电池等方面有着广泛的应用前景。钙钛矿在室温下具有稳定的激子和大的振子强度，研究其激子与光子的强耦合以及增益性质对于构建低阈值微纳激光器件和光逻辑器件有着重要意义。本项目首先利用化学气相沉积法和溶液旋涂法制备了不同形态的三维（3D）和二维（2D）结构钙钛矿晶体材料，包括纳米片，纳米线，钙钛矿多晶薄膜等。在此基础上我们构建了钙钛矿异质结结构和钙钛矿光学微腔结构等。本项目揭示了钙钛矿光学微腔中光子与激子的强相互作用和激子-激子散射对发光、激射等性能的影响；发现了非均一相R-P钙钛矿间的能量转移能抑制俄歇复合，降低激光阈值；同时在钙钛矿异质结中观察到了较大的光学非线性响应。此外，我们利用钙钛矿/分布式布拉格反射镜腔实现了室温下束缚态的激子极化激元凝聚，并揭示了钙钛矿纳米线中激子极化激元传输对其吸收和折射率的调控机制，这一发现对于构建极化激元相关功能器件具有重要意义。另外，我们在钙钛矿薄膜和单晶微米片测得了超高的光学增益，这为构建钙钛矿的激子极化激元传输和光开关器件奠定了基础。