Room-Temperature Coherent Optical Phonon in 2D Electronic Spectra of CH3NH3PbI3 Perovskite as a Possible Cooling Bottleneck
Room-Temperature Coherent Optical Phonon in 2D Electronic Spectra of CH3NH3PbI3 Perovskite as a Possible Cooling Bottleneck
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DOI：
10.1021/acs.jpclett.7b01357
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发表时间：
2017-07-20
影响因子：
5.7
通讯作者：
Fleming, Graham R.
中科院分区：
文献类型：
--
作者：
Monahan, Daniele M.;Guo, Liang;Fleming, Graham R.
一个热声子瓶颈可能是负责缓慢的热载流子冷却甲基铵碘化铅混合钙钛矿，创造更有效的热载流子光致发光的潜力。在室温2D电子光谱附近的带边，我们观察到的振幅振荡，由于一个显着长寿命的0.9太赫兹相干声子人口在室温下。这个声子（或一组声子）被分配到Pb-I晶格的角变形，而不是耦合到阳离子旋转。电子跃迁和0.9 THz模式之间的强耦合，以及与其他声子模式的相对隔离，使得可能导致声子瓶颈。2D光谱的泵浦频率分辨率也使得能够独立地观察光致反射和漂白，并确认由于带隙重整化的特征比瞬态吸收光谱中的特征寿命更长。
A hot phonon bottleneck may be responsible for slow hot carrier cooling in methylammonium lead iodide hybrid perovskite, creating the potential for more efficient hot carrier photovoltaics. In room-temperature 2D electronic spectra near the band edge, we observe amplitude oscillations due to a remarkably long lived 0.9 THz coherent phonon population at room temperature. This phonon (or set of phonons) is assigned to angular distortions of the Pb-I lattice, not coupled to cation rotations. The strong coupling between the electronic transition and the 0.9 THz mode(s), together with relative isolation from other phonon modes, makes it likely to cause a phonon bottleneck. The pump frequency resolution of the 2D spectra also enables independent observation of photoinduced absorptions and bleaches independently and confirms that features due to band gap renormalization are longer-lived than in transient absorption spectra.