二维材料及其异质结构由于其独特的结构和优异的光电性能，有望成为下一代光电子技术的核心材料。光生载流子的动力学性质对这些材料的光电性能具有重要的影响。本文综述了近年来对这些材料中光生载流子动力学过程的研究进展。在时域动力学方面，介绍了利用基于超快激光的瞬态吸收光谱技术所揭示的二维材料中的载流子热化、能量弛豫、激子形成、激子?激子湮灭、以及激子复合等物理过程。在空域动力学方面，讨论了利用具有高空间分辨率的瞬态吸收显微技术来研究光生载流子在二维材料平面内的输运过程。在此基础上，进一步讨论了二维材料异质结构中的电荷及能量在层间转移的过程。

Two-dimensional Dion–Jacobson (D-J) phase perovskites are prospective photovoltaic and optoelectronic materials. To study their mechanical properties and carrier-lattice interactions, we conduct femtosecond spectroscopic experiments on the films of a D-J perovskite. After optical excitation, a ∼33meV bandgap oscillation is observed in the film by transient absorption spectroscopy. With the help of transient reflection methods, we reveal that the oscillation originates from the transport of coherent longitudinal acoustic phonons through the film. Large bandgap oscillation indicates a strong coupling between carriers and lattice, and significant bandgap modulation by strains in D-J perovskites.

The aggregation and photoinduced excited state dynamics of organic π-conjugated molecules play a vital role in solar energy conversion and applications. This work investigates how solvent polarity affects the aggregation behavior and the photophysical process of perylene diimide dimer (PDI-II). The results show that the conjugations between PDI intramolecular chromophores are more likely to generate excimer, and the conjugations between PDI intermolecular chromophores are more likely to experience symmetry-breaking charge separation. Our study can provide a reference for the design of high-efficiency solar energy conversion materials.

Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years, the influence of temperature and the type of the employed hole transport layer (HTL) on the charge carrier dynamics and recombination processes in perovskite photovoltaic devices is still largely unexplored. In particular, significant knowledge is missing on how these crucial parameters for radiative and non-radiative recombinations, as well as for efficient charge extraction vary among different perovskite crystalline phases that are induced by temperature variation. Herein, we perform micro photoluminescence (μPL) and ultrafast time resolved transient absorption spectroscopy (TAS) in Glass/Perovskite and two different Glass/ITO/HTL/Perovskite configurations at temperatures below room temperature, in order to probe the charge carrier dynamics of different perovskite crystalline phases, while considering also the effect of the employed HTL polymer. Namely, CH₃NH₃PbI₃ films were deposited on Glass, PEDOT:PSS and PTAA polymers, and the developed Glass/CH₃NH₃PbI₃ and Glass/ITO/HTL/CH₃NH₃PbI₃ architectures were studied from 85 K up to 215 K in order to explore the charge extraction dynamics of the CH₃NH₃PbI₃ orthorhombic and tetragonal crystalline phases. It is observed an unusual blueshift of the bandgap with temperature and the dual emission at temperature below of 100 K and also, that the charge carrier dynamics, as expressed by hole injection times and free carrier recombination rates, are strongly depended on the actual pervoskite crystal phase, as well as, from the selected hole transport material.Despite that organic-inorganic lead halide perovskites have attracted enormous scientific attention for energy conversion applications over the recent years, the influence of temperature and the type of the employed hole transport layer (HTL) on the charge carrier dynamics and recombination processes in perovskite photovoltaic devices is still largely unexplored. In particular, significant knowledge is missing on how these crucial parameters for radiative and non-radiative recombinations, as well as for efficient charge extraction vary among different perovskite crystalline phases that are induced by temperature variation. Herein, we perform micro photoluminescence (μPL) and ultrafast time resolved transient absorption spectroscopy (TAS) in Glass/Perovskite and two different Glass/ITO/HTL/Perovskite configurations at temperatures below room temperature, in order to probe the charge carrier dynamics of different perovskite crystalline phases, while considering also the effect of the employed HTL polymer. Namely, CH₃NH₃PbI₃ films were deposited on Glass, PEDOT:PSS and PTAA polymers, and the developed Glass/CH₃NH₃PbI₃ and Glass/ITO/HTL/CH₃NH₃PbI₃ architectures were studied from 85 K up to 215 K in order to explore the charge extraction dynamics of the CH₃NH₃PbI₃ orthorhombic and tetragonal crystalline phases. It is observed an unusual blueshift of the bandgap with temperature and the dual emission at temperature below of 100 K and also, that the charge carrier dynamics, as expressed by hole injection times and free carrier recombination rates, are strongly depended on the actual pervoskite crystal phase, as well as, from the selected hole transport material.

Two-dimensional (2D) Sn-based perovskites are a kind of non-toxic environment-friendly emission material with low photoluminescence quantum yields (PLQYs) and enhanced emission linewidths compared to that of 2D Pb-based perovskites. However, there is no work systematically elucidating the reasons for the differences in the emission properties. We fabricate (BA)2SnI4 and (BA)2PbI4 having different defect densities and different exciton-phonon scattering intensities. We also reveal that 2D Sn-based perovskites have stronger exciton-phonon scattering intensity and higher defects density, significantly broadening the emission linewidth and accelerating the exciton relaxation process, which significantly reduces the PLQY of 2D Sn-based perovskites.

利用飞秒瞬态吸收光谱对三个经不同处理且光电性能有明显差异的NDT基异质结薄膜（无己基取代混合膜， 己基取代混合膜以及己基取代并做溶剂退火处理的混合膜）进行了研究。结果显示这三个异质结薄膜，其电荷分离态大部分都是由激子态直接演化来的，并没有经过电荷转移态。在这三个混合膜中，己基取代并做溶剂退火处理的混合膜表现出最大电荷分离产率，己基取代但不经过溶剂退火处理的混合膜拥有最长的电荷分离态寿命。结合它们的电子-空穴迁移率，从动力学的角度给出了己基取代及溶剂退火处理增强光电转换效率的原因在于提高了电荷分离态寿命、增强了电荷分离产率以及平衡了电子-空穴迁移率。此研究可为将来优化光电转换效率提供参考。