Franco Carolina Villamil, Mahler Benoît, Cornaggia Christian, Gustavsson Thomas, Cassette Elsa
Université Paris-Saclay, CEA, CNRS, Laboratoire Interactions, Dynamiques et Lasers (LIDYL), 91191 Gif-sur-Yvette, France.
Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière (ILM), F-69622 Villeurbanne, France.
Nanomaterials (Basel). 2020 Sep 23;10(10):1897. doi: 10.3390/nano10101897.
We study the hot charge carrier relaxation process in weakly confined hybrid lead iodide perovskite colloidal nanostructures, FAPbI (FA = formaminidium), using femtosecond transient absorption (TA). We compare the conventional analysis method based on the extraction of the carrier temperature () by fitting the high-energy tail of the band-edge bleach with a global analysis method modeling the continuous evolution of the spectral lineshape in time using a simple sequential kinetic model. This practical approach results in a more accurate way to determine the charge carrier relaxation dynamics. At high excitation fluence (density of charge carriers above 10 cm), the cooling time increases up to almost 1 ps in thick nanoplates (NPs) and cubic nanocrystals (NCs), indicating the hot phonon bottleneck effect. Furthermore, Auger heating resulting from the multi-charge carrier recombination process slows down the relaxation even further to tens and hundreds of picoseconds. These two processes could only be well disentangled by analyzing simultaneously the spectral lineshape and amplitude evolution.
我们使用飞秒瞬态吸收光谱（TA）研究了弱受限的混合碘化铅钙钛矿胶体纳米结构FAPbI₃（FA = 甲脒）中的热载流子弛豫过程。我们将基于通过用全局分析方法拟合带边漂白的高能尾部来提取载流子温度（）的传统分析方法与使用简单的顺序动力学模型对光谱线形随时间的连续演变进行建模的全局分析方法进行了比较。这种实用方法为确定电荷载流子弛豫动力学提供了一种更准确的方法。在高激发通量（电荷载流子密度高于10¹⁹ cm⁻³）下，厚纳米板（NPs）和立方纳米晶体（NCs）中的冷却时间增加到近1 ps，这表明存在热声子瓶颈效应。此外，多电荷载流子复合过程导致的俄歇加热使弛豫进一步减慢至数十和数百皮秒。只有通过同时分析光谱线形和振幅演变，才能很好地分辨这两个过程。
