Computational Prediction of Structural, Electronic, and Optical Properties of Organic-Inorganic Hybrid Materials for Lighting Applications

晶态有机-无机杂化钙钛矿可以在纳米尺度上将有机和无机分子的性质相互交织在一起，并对形成的原子结构进行理想的精确控制。因此，它们提供了广泛的机会来寻找具有高度可调特性的全新材料。这项工作的目的是预测用于发光器件(LED)的新型二维有机-无机复合钙钛矿的可能存在及其激子和光学性质。因此，基于遗传算法探索分子构型空间的有机-无机杂化钙钛矿材料的晶体结构预测方法。为了降低预测方法的计算成本，将扩展一个力场(万有力场)，以允许描述二维有机-无机杂化钙钛矿。预测方法的可靠性将通过已知晶体结构的化合物进行测试。我们将在密度泛函理论的框架下，利用杂化泛函对预测方法所预测的构象电子结构进行研究，以确定它们是否适合作为发光二极管。到项目结束时，有机晶体中激子和晶格振动相互作用的模型将被用来描述二维有机-无机杂化钙钛矿中的激子效应和发射光谱。力场和CSPM都将在本项目范围之外适用于研究和筛选新的有机-无机杂化钙钛矿及其光激子性质，例如，对于在拟议工作中采样的分子以外的其他LED，或者用于光伏应用。

Crystalline organic-inorganic hybrid perovskites allow to intertwine the properties of organic and inorganic molecules at the nanoscale with ideally exact control over the atomic structure formed. Thus, they offer a wide range of opportunities to find completely new materials with highly tunable properties. The aim of this work is to predict the possible existence of new two-dimensional hybrid organic-anorganic perovskites for light emitting device (LED) application and their excitonic and optical properties. Hence, a crystal structure prediction method for organic-inorganic hybrid perovskite materials will be developed, based on a genetic algorithm to explore the molecular configuration space. To lower the computational cost of the prediction method, a force field (the Universal Force Field) will be expanded to allow the description of two-dimensional organic-inorganic hybrid perovskites. The reliability of the prediction method will be tested with compounds whose crystal structure is already known. The electronic structure of conformers suggested by the prediction method will be investigated using hybrid functionals in the framework of density functional theory to determine their suitability as LEDs. Towards the end of the project, a model for the interaction of excitons and lattice vibrations in organic crystals will be adapted to describe excitonic effects and emission spectra in two-dimensional organic-inorganic hybrid perovskites.Both the force field and the CSPM will be applicable beyond the scope of this project to investigate and screen for new organic-inorganic hybrid perovskites and their optoexcitonic properties, e.g. for other LEDs beyond the molecules sampled in the proposed work or for photovoltaic application.