Monitoring Charge Carrier Diffusion across a Perovskite Film with Transient Absorption Spectroscopy.,The Journal of Physical Chemistry Letters

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Monitoring Charge Carrier Diffusion across a Perovskite Film with Transient Absorption Spectroscopy.
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2020-01-02 , DOI: 10.1021/acs.jpclett.9b03427
Hannu P Pasanen ₁ , Paola Vivo ₁ , Laura Canil ₂ , Hannes Hempel ₂ , Thomas Unold ₂ , Antonio Abate _{2,

3} , Nikolai V Tkachenko ₁

Affiliation

We have developed a new noninvasive optical method for monitoring charge carrier diffusion and mobility in semiconductor thin films in the direction perpendicular to the surface which is most relevant for devices. The method is based on standard transient absorption measurements carried out in reflectance and transmittance modes at wavelengths below the band gap where the transient response is mainly determined by the change in refractive index, which in turn depends on the distribution of photogenerated carriers across the film. This distribution is initially inhomogeneous because of absorption at the excitation wavelength and becomes uniform over time via diffusion. By modeling these phenomena we can determine the diffusion constant and respective mobility. Applying the method to a 500 nm thick triple cation FAMACs perovskite film revealed that homogeneous carrier distribution is established in few hundred picoseconds, which is consistent with mobility of 66 cm2 (V s)-1.

中文翻译：

用瞬态吸收光谱法监测钙钛矿薄膜上的电荷载流子扩散。

我们已经开发了一种新的非侵入性光学方法，用于监测与器件最相关的垂直于表面方向的半导体薄膜中的载流子扩散和迁移率。该方法基于在带隙以下波长处以反射和透射模式进行的标准瞬态吸收测量，其中瞬态响应主要取决于折射率的变化，而折射率的变化又取决于整个薄膜上光生载流子的分布。由于在激发波长处的吸收，该分布最初是不均匀的，并且随着时间的流逝通过扩散变得均匀。通过对这些现象进行建模，我们可以确定扩散常数和相应的迁移率。

更新日期：2020-01-02

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