El-Zohry Ahmed M, Turedi Bekir, Alsalloum Abdullah, Maity Partha, Bakr Osman M, Ooi Boon S, Mohammed Omar F
Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Department of Physics, AlbaNova Center, Stockholm University, 10691, Stockholm, Sweden.
Commun Chem. 2022 May 30;5(1):67. doi: 10.1038/s42004-022-00683-7.
Studying the charge dynamics of perovskite materials is a crucial step to understand the outstanding performance of these materials in various fields. Herein, we utilize transient absorption in the mid-infrared region, where solely electron signatures in the conduction bands are monitored without external contributions from other dynamical species. Within the measured range of 4000 nm to 6000 nm (2500-1666 cm), the recombination and the trapping processes of the excited carriers could be easily monitored. Moreover, we reveal that within this spectral region the trapping process could be distinguished from recombination process, in which the iodide-based films show more tendencies to trap the excited electrons in comparison to the bromide-based derivatives. The trapping process was assigned due to the emission released in the mid-infrared region, while the traditional band-gap recombination process did not show such process. Various parameters have been tested such as film composition, excitation dependence and the probing wavelength. This study opens new frontiers for the transient mid-infrared absorption to assign the trapping process in perovskite films both qualitatively and quantitatively, along with the potential applications of perovskite films in the mid-IR region.
研究钙钛矿材料的电荷动力学是理解这些材料在各个领域出色性能的关键一步。在此，我们利用中红外区域的瞬态吸收，在该区域仅监测导带中的电子信号，而不受其他动力学物种的外部影响。在4000 nm至6000 nm（2500 - 1666 cm）的测量范围内，可以轻松监测激发载流子的复合和俘获过程。此外，我们发现，在该光谱区域内，俘获过程可以与复合过程区分开来，其中与溴化物基衍生物相比，碘化物基薄膜表现出更倾向于俘获激发电子的趋势。俘获过程归因于在中红外区域释放的发射，而传统的带隙复合过程则未显示出此类过程。已经测试了各种参数，如薄膜组成、激发依赖性和探测波长。这项研究为瞬态中红外吸收开辟了新的前沿领域，可对钙钛矿薄膜中的俘获过程进行定性和定量分析，以及钙钛矿薄膜在中红外区域的潜在应用。
