Fundamental Study of Dopants Effect for Stable Hybrid Perovskite Materials

非技术描述：掺杂剂控制和调节各种电子，光学，热学和机械性能，因此在金属，半导体和绝缘体等各种材料研究中发挥着关键作用。因此，掺杂剂对新兴材料影响的基本见解提供了一个通用的工具包，可以从根本上定制材料特性，以最佳地适应其所需的实际应用，甚至导致新材料和应用的发现。有机-无机杂化钙钛矿材料（HPM）作为光致发光领域的一个改变游戏规则的参与者，表现出令人印象深刻的光伏效率。然而，HPM仍然遭受主要挑战，包括化学不稳定性和铅毒性，这是由于：（i）水合作用，导致结构失效和（ii）空位缺陷的形成，导致载流子寿命差。在这个项目中，研究小组的目标是了解HPM中的各种掺杂剂，并根据基本化学原理追求它们对稳定HPM的协同效应。同时，作为培养下一代科学家的有效途径，该团队旨在通过与阿贡国家实验室科学家的现有合作，与附近的世界一流研究设施合作，使具有广泛知识的研究生和本科生都可以在年轻时参与前线研究项目，并接受尖端设施，跨学科知识，批判性思维，解决问题和团队合作。技术说明：该项目有两个目标，即建立掺杂剂（类型，数量和位置）和HPM的化学稳定性之间的关系，同时最大限度地减少PV性能的损失;并提供原子水平的理解，以了解拟议的掺杂剂如何稳定HPM中的易受攻击的离子并影响其PV性能。进行阳离子和阴离子的协同共掺杂以研究它们对整体化学稳定性的影响。该团队还在探索电荷各向同性阳离子掺杂剂和多价阴离子掺杂剂之间的相互作用，假设它们可以增强HPM中阳离子和阴离子部分之间的静电耦合，从而使整个钙钛矿结构具有更大的刚性。该研究涉及使用能够在钙钛矿结构的原子水平网关处形成强氢键的掺杂剂，以有效地阻止水分子的进入。此外，该研究还涉及使用选定的还原性掺杂剂来抑制Sn基HPM中Sn 2+氧化为Sn 4+，基于对还原剂可以延缓Sn 2+氧化的理解。此外，高压技术用于最小化Sn基HPM中的Sn 2+空位缺陷。通过谨慎地设计掺杂剂的类型、量和位置以使PV效率的损失最小化并且使掺杂剂的稳定性增强最大化，最终的研究目标是提供一个清晰的路径，以原子增强结构的HPM使用掺杂剂作为稳定铆钉，以实现稳定和铅，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Description: Dopants govern and regulate a variety of electronic, optical, thermal and mechanical properties, thus playing a pivotal role in various materials research ranging from metals, semiconductors and insulators. Therefore, fundamental insights to the dopants effect on emerging materials provide a versatile kit to radically tailor the material properties to best fit in their desired practical applications and even lead to discovery of new materials and applications. As a game-changing player in the field of photovoltaics, organic-inorganic hybrid perovskites materials (HPM) has exhibited impressive photovoltaic efficiency. However, HPM still suffer from major challenges including chemical instability and lead toxicity due to: (i) hydration effects, leading to structural failure and (ii) formation of vacancy defects, leading to poor carrier lifetime. In this project, the research team aims to understand the various dopants in HPM and to pursue their synergistic effect towards stable HPM based on fundamental chemical principles. Meanwhile, as an effective way to train the next generation of scientists, the team aims to work with the nearby world-class research facilities at Argonne National Laboratory through existing collaborations with Argonne scientists such that both graduate and undergraduate students with wide diversities can be involved in frontline research projects at their young age, and trained with skills in cutting-edge facilities, interdisciplinary knowledge, critical thinking, problem solving, and team work. Technical Description: The project has a two-fold objective, namely to establish the relationship between dopants (type, amount and location) and the chemical stability of the HPM while minimizing the loss in PV performance; and to provide an atomic level understanding of how the proposed dopants stabilize the vulnerable ions in HPM and affect their PV performance. A synergistic co-doping of both cations and anions is conducted to study their effect on the overall chemical stability. The team is also exploring the interplay between charge-isotropic cationic dopants and multivalent anionic dopants, which are hypothesized to enhance electrostatic coupling between the cationic and anionic parts in HPM, and thus enabling greater rigidity of the overall perovskite structure. The research involves the use of dopants capable of forming strong hydrogen bonding at the atomic level gateway of the perovskite structure to effectively block the ingression of water molecules. Furthermore, the research also involves the use of selected reducing dopants to suppress oxidation of Sn2+ to Sn4+ in Sn-based HPM, based on understanding of what and how reductants can retard the oxidation of Sn2+. Additionally, a high pressure technique is used to minimize the Sn2+ vacancy defects in Sn-based HPM. By prudently designing the type, amount and location of the dopants towards minimal loss in PV efficiency and maximal stability enhancement benefited from the dopants, the ultimate research goal is to provide a clear path to atomically reinforced structure of HPM using dopants as the stabilizing rivets in order to achieve stable and lead-free perovskite solar cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.