研究目的
To compare the properties of the two-dimensional (2D) (BA)2(MA)Pb2I7 and three-dimensional (3D) MAPbI3 materials and evaluate the different impacts that the 2D-confined spacer layer of butylammonium cations and the 3D-confined methylammonium cations have on the charge carrier dynamics in the two systems.
研究成果
The study revealed faster hot-electron relaxations in 2D (BA)2(MA)Pb2I7 than in 3D MAPbI3, attributed to the larger non-adiabatic couplings in the 2D system due to contributions from coupled vibronic modes between the BA+ organic spacer cations and the Pb-I framework. This suggests that tuning the structure of the organic spacer cations can modulate the performance of optoelectronic devices based on 2D perovskites.
研究不足
The spin-orbital coupling (SOC) and many-body effects are not included due to their extremely high computational cost. The excitonic effects in thin 2D perovskites are much stronger than in 3D systems, but the proper evaluation of the excitonic effects requires a time-dependent version of Bethe-Salpeter theory, which is still under development.
1：Experimental Design and Method Selection:
Non-adiabatic molecular dynamics simulations combined with time-dependent density functional theory calculations were used to compare the properties of the 2D (BA)2(MA)Pb2I7 and 3D MAPbI3 materials.
2：Sample Selection and Data Sources:
The study focused on the 2D (BA)2(MA)Pb2I7 and 3D MAPbI3 materials.
3：List of Experimental Equipment and Materials:
QuantumEspresso package (version 6.1) for geometry optimizations, electronic-structure calculations, and ab initio molecular dynamics simulations; PYXAID package for time-domain NAMD process.
4：1) for geometry optimizations, electronic-structure calculations, and ab initio molecular dynamics simulations; PYXAID package for time-domain NAMD process. Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: The methodology involved ab initio MD simulations with various constraints to quantify the contributions of BA+ and MA+ cations to the structural fluctuations of the [Pb2I7]3- framework.
5：Data Analysis Methods:
The population decay curve was fitted using a Gaussian plus exponential function to calculate the relaxation time.
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