Computer-aided design of functional materials for optoelectronic application

今天，有限元模拟通常用于工程分析各种设计方案。然而，计算机建模在探索新材料中的作用通常仅限于解释实验观察结果，而不是促进发现具有特定应用特性的材料。计算机辅助材料设计方法的成功依赖于该理论将新化合物的原子结构与其第一原理性质联系起来的能力，即，理想情况下没有任何先验经验知识。拟议的研究计划旨在推进量子力学方法，以模拟和发明新型功能材料，用于广泛的光电应用（激光器，太阳能电池，发光二极管等）。在即将到来的资金期内，我们计划专注于开发可用于电信网络半导体激光器的光学增益材料。这种新材料系统有望改善远距离光纤网络中光源的热管理和效率。为了实现这一目标，我们将致力于半导体激光器材料建模的完全第一性原理方法。重点将放在对化合物半导体合金中不可避免地存在的组成无序的明确描述，及其对激光增益介质的光学跃迁和损耗特性的影响。一个预测的定量理论将实现相结合的量子力学模型的激光增益与细节的腔内损耗从密度泛函理论计算评估。这种创新的特点使得新方法上级以前的微观模型的基础上流行的k. p理论，这是不能够捕捉的影响，无序和本地化。量化内在的“无序惩罚”将使我们能够为进一步改进现有技术提供基准，并评估新兴材料系统的潜力。关于半导体异质结构中的非辐射损耗所获得的新知识对于其他电子器件（例如光伏器件和发光二极管）具有根本重要性。拟议研究的成功最终可以将范式转向理论指导的功能材料选择，以适应特定的应用，然后再进行电子设备的制造和表征。

Today finite element simulations are routinely used in engineering for analysis of various design alternatives. However, the role of computer modelling in exploration of novel materials is often limited to interpretation of experimental observations rather than facilitation the discovery of materials with properties tailored to specific applications. The success of a computer-aided material design approach relies on an ability of the theory to relate the atomic structure of novel compounds to their properties from first principles, i.e., ideally without any prior empirical knowledge. The proposed research program aims at advancement of quantum-mechanical approaches to the simulation and invention of novel functional materials for a broad spectrum of optoelectronic applications (lasers, solar cells, light emitting diodes, etc.).******In the upcoming funding period, we plan to focus on the development of optical gain materials that can be used in semiconductor lasers for telecommunication networks. The new material system is expected to improve the heat management and efficiency of the light source in long-range fiber-optic networks. In order to fulfill this goal, we will work towards a fully first-principle approach to the modelling of semiconductor laser materials. The emphasis will be placed on an explicit description of compositional disorder, which is inevitably present in compound semiconductor alloys, and its implication in optical transitions and loss characteristics of the laser gain medium. A predictive quantitative theory will be achieved by combining a quantum-mechanical model of the laser gain with details of intra-cavity losses evaluated from density functional theory calculations. This innovative feature makes the new method superior to previous microscopic models based on popular k.p theory, which are not capable of capturing effects of disorder and localisation. Quantifying the intrinsic "disorder penalty" will allow us to provide a benchmark for further improvement of existing technologies and assess the potential of emerging material systems. The new knowledge obtained about non-radiative losses in semiconductor heterostructures is of fundamental importance to other electronic devices, such as photovoltaic devices and light-emitting diodes. The success of the proposed study can ultimately shift the paradigm towards theory-guided selection of functional materials tailored to specific applications prior to undertaking fabrication and characterisation of electronic devices.