DMREF: SusChEM: Simulation-Based Predictive Design of All-Organic Phosphorescent Light-Emitting Molecular Materials

DMREF：SUSCHEM：基于模拟的全有机磷光发光分子的预测设计非吸收技术描述：有机发光二极管（OLED）在从城市照明到大屏幕显示面板的应用中表现出显着的能效。 目前的技术是基于磷光材料，含有有机金属化合物，其中涉及重金属离子。这些是昂贵的采购，目前的限制方面的设备寿命，并在某些情况下，被认为是环境不安全，甚至有毒。 这项研究的目标是通过开发一种全新的全有机磷光分子来消除对重金属离子的需求。 主要任务是设计这样的分子，其中电子轨道的并置促进磷光的潜在过程，而同时化学键合模式提供所需的结构刚性，以最大限度地减少电子激发的非辐射衰减。 为此，采用综合计算实验方法，其中分子模拟，化学合成和材料表征相结合的协同和迭代序列。 该项目的预期成果是基于可持续化学的新型环保磷光材料，可立即用于照明应用。 在完善无金属OLED的同时，对分子材料功能响应的新见解使有机电子产品受益匪浅，并推动了光电子学、传感器和显示器等先进技术的发展。 最后，基于模拟的预测性材料设计的软件工具包、数据管理工具和工作流程被确立为材料开发的新范式。技术说明：磷光材料的效率是基于不仅从单重态发射而且从三重态发射的能力，这些激发态是由于自旋轨道耦合而填充的。这种耦合的强度归因于有机金属化合物中重金属离子的存在。然而，有机金属伴随着重大挑战：除了贵金属的高成本之外，发射层中的错位金属离子可能捕获电荷，这危及器件寿命。意外的是，co-PI展示了无金属有机磷光体，在环境条件下具有前所未有的高达68%的固态磷光量子产率。目前的研究旨在进一步开发这种全新的，环境友好的，化学可持续的全有机磷光分子，通过采用综合计算实验方法来改善性能特性。具体目标是（i）从发射分子中消除重金属离子，目的是降低材料成本和可获得性，提高制造的容易性，并延长器件寿命和可靠性;（ii）消除卤素键合的双重作用，即，促进自旋-轨道耦合，抑制振动能量耗散，用分子内类似物取代分子间二级键诱导的磷光增强机制;（iii）优化发射物质和主体物质的分子结构，以便通过分子内键合模式的硬化使激发态的振动介导的非辐射衰变最小化，通过主体分子稳定发射体，所述主体分子被设计为抑制有效堆积的几何形状内的有害振动，以及在纳米限制内结晶发射体。为此，构建了概念发射体和主体分子，并研究了它们的结构和电子性质，例如，激发态能量、单重态-三重态跃迁速率、电荷迁移率等，使用第一原理计算预测。使用形状填充算法和分子模拟生成结构模型，并预测可能的晶体结构。最好的候选分子合成，表征，并测量其发射和振动特性。

DMREF: SUSCHEM: SIMULATION-BASED PREDICTIVE DESIGN OF ALL-ORGANIC PHOSPHORESCENT LIGHT-EMITTING MOLECULAR MATERIALSNon-technical Description: Organic light emitting diodes (OLED) exhibit remarkable energy efficiency in applications ranging from urban lighting to large-screen display panels. Current technologies are based on phosphorescent materials that contain organo-metallic compounds, which involve heavy-metal ions. These are expensive to procure, present limitations with regard to device longevity, and in some cases are considered environmentally unsafe or even toxic. The goal of this research is to eliminate the need for heavy-metal ions by developing a fundamentally new class of all-organic phosphorescent molecules. The principal task is to design molecules in which the juxtaposition of electronic orbitals promotes the processes underlying phosphorescence while at the same time the chemical bonding patterns provide the structural rigidity needed to minimize the non-radiative decay of electronic excitations. To this end an integrative computational-experimental approach is employed, in which molecular simulations, chemical synthesis, and materials characterization are combined in a synergistic and iterative sequence. The expected outcomes of this project are novel environmentally benign phosphorescent materials that are based on sustainable chemistries and that are immediately deployable for lighting applications. The new insights into the functional response of molecular materials gained while perfecting metal-free OLED benefits organic electronics in general, and advance technologies such as photovoltaics, sensors, and displays. Finally, software toolkits, data management utilities, and workflows for simulation-based predictive materials design are established as a new paradigm for materials development.Technical Description: The efficiency of phosphorescent materials is based on the ability to emit not only from singlet but also triplet excited states, which are populated as a result of spin-orbit coupling. The strength of this coupling is attributed to the presence of heavy-metal ions in organo-metallic compounds. However, organo-metallics are accompanied by significant challenges: besides the high cost of precious metals, dislocated metal ions in the emitting layer may trap charge, which jeopardizes device longevity. By serendipity, the co-PI demonstrated metal-free organic phosphors with unprecedented high solid-state phosphorescent quantum yield of up to 68% at ambient conditions. The current research aims to further develop this fundamentally new, environmentally benign, and chemically sustainable class of all-organic phosphorescent molecules with improved performance characteristics by employing an integrated computational-experimental approach. Specific objectives are to (i) eliminate the heavy metal ions form the emitting molecules with the aim to lower materials cost and obtainability, improve ease of fabrication, and prolong device lifetime and dependability; (ii) deconvolute the dual roles of halogen bonding, i.e., to promote spin-orbit coupling and suppress vibrational energy dissipation, and supplant the intermolecular secondary bonding-induced phosphorescence enhancement mechanism with intramolecular analogs; (iii) optimize the molecular architectures of both the emitting and host species so as to minimize vibration-mediated non-radiative decay of excited states through stiffening of intramolecular bonding patterns, stabilization of emitters by host molecules designed to suppress detrimental vibrations within effectively packed geometries, and crystallization of emitters within nano-confinement. To this end, concept emitter and host molecules are constructed and their structure and electronic properties, e.g., excited state energies, singlet-triplet transition rates, charge mobilities, etc., predicted using first-principles calculations. Structural models are generated using shape packing algorithms and molecular simulations, and possible crystal structures are predicted. Best candidate molecules are synthesized, characterized, and their emissive and vibrational properties measured.