CAREER: Manipulating Photon Energy by Perovskite-Sensitized Solid-State Upconversion

非技术描述太阳能对于继续满足当今社会的能源需求至关重要。提高太阳能电池性能的一个途径是增加可用于发电的太阳光比例。太阳的大部分光被浪费了，因为它由低能量的光子组成，这些光子不被用于制造太阳能电池的半导体吸收。通过一种称为上转换的过程将低能光子转化为高能光子，可以使低能光子变得可用。例如，两个能量较低的红外光子可以转化为能量较高的可见光光子。该项目将使用有机分子和金属卤化物钙钛矿的组合，这些有机分子可以实现上转换过程，目前正在研究用于太阳能电池。钙钛矿将被用来吸收低能量的光并激发有机分子。在成功上转换后，更高能量的光可以被吸收用于太阳能电池。光学技术和显微技术的结合将导致对潜在过程的详细了解。除了这个项目的科学影响，一个目标是通过在本科生研究和教育中的强大指导，引导学生进一步追求科学事业，并激发他们的独立研究、批判性思维和创造性解决问题的能力。这项活动旨在激励新一代科学家。为了弥合科学家和非科学界之间日益扩大的裂痕，将通过外展讲座和通过当地电视和社交媒体发布的科学交流(‘厨房化学’或‘厨房光谱学’)，建立一个强大的基础，将PI的机构与当地社区联系起来。技术说明有效地将太阳能转换为化学或电能是满足我们社会未来能源需求的关键。通过在钙钛矿/有机半导体界面产生三重态的上转换过程来提高光子利用率，是一种非常有前途的提高光激发态寿命和整体器件效率的方法。主要的研究人员将通过三重态-三重态湮没来探索钙钛矿敏化的固态上转换，以揭示微尺度和纳米尺度的分子排列在OSCs中的作用。光学光谱和扫描探针显微镜的结合将被用来阐明起源于钙钛矿衬底上特定分子排列的聚并苯的局部光电性质。通过分子放置控制轨道耦合将允许系统地评估所涉及的步骤。主要目的是了解为什么常用的在溶液中表现出高效率的零化器(例如二苯基菲)在固态中不能产生可转移的结果，以及如何利用或避免聚集效应来提高固态上转换效率。为了实现这一目标，将开发新的钙钛矿/三重态受主对，以研究为什么基于溶液的三重态湮没材料在固态下表现不佳。利用光学扫描探针显微镜和时间分辨光学光谱研究了分子间局域相互作用对上转换过程的影响。从系综到原子尺度的表征方法的组合将揭示管理钙钛矿型/OSC基混合TTA上转换的整体光电性质的局部结构-性质关系。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical DescriptionSolar energy is crucial to continue to meet the energy demands of today’s society. One pathway toward increasing the performance of solar cells is to increase the portion of sunlight that can be used to generate electricity. Much of the sun’s light is wasted because it consists of low-energy photons which are not absorbed by the semiconductors used to make solar cells. Low energy photons can be made usable by transforming them into higher energy photons through a process called upconversion. For example, two low-energy infrared photons can be converted into a higher-energy visible photon. This project will use a combination of organic molecules known to enable the upconversion process and metal halide perovskites, which are currently being investigated for use in solar cells. The perovskite will be used to absorb the low energy light and excite the organic molecules. Upon successful upconversion, higher energy light can then be absorbed for use in a solar cell. A combination of optical techniques and microscopy will lead to a detailed understanding of the underlying processes. Beyond the scientific impact of this project, a goal is to guide students to further pursue a scientific career and inspire their independent research, critical thinking, and creative problem-solving capabilities by strong mentorship in undergraduate research and education. This activity aims to inspire a new generation of scientists. To close the growing rift between scientists and the non-scientific community, a strong foundation linking the PI’s institution with the local community will be built by outreach lectures and science communication (‘Kitchen Chemistry’ or ‘Kitchen Spectroscopy’) via local TV and social media outlets.Technical DescriptionEfficient interconversion of solar energy to chemical or electrical energy is the key to meeting the future energy demands of our society. Improved photon utilization through an upconversion process involving triplet generation at the perovskite/organic semiconductor interface is a very promising approach to increase the photoexcited state lifetime and therefore, overall device efficiencies. The principal investigator will explore perovskite-sensitized solid-state upconversion via triplet-triplet annihilation to unravel the role of microscale and nanoscale molecular arrangement in OSCs. A combination of optical spectroscopy and scanning probe microscopy will be employed to elucidate the local optoelectronic properties originating from specific molecular arrangements of polyacenes on perovskite substrates. Control over orbital coupling by molecular placement will allow the involved steps to be systematically evaluated. The main goal is to understand why commonly utilized annihilators which exhibit high efficiencies in solution (e.g., diphenylanthracene) do not yield transferable results in the solid state, and how aggregation effects can be harnessed or avoided to improve solid-state upconversion yields. To achieve this goal, new perovskite/triplet acceptor pairs will be developed to investigate why promising solution-based triplet annihilators perform poorly in the solid state. The effect of local intermolecular interactions on the upconversion process will be studied on the microscale and the nanoscale using optical scanning probe microscopy and time-resolved optical spectroscopy. The combination of characterization methods spanning from the ensemble to the atomic scale will reveal the local structure-property relationships governing the bulk optoelectronic properties of hybrid perovskite/OSC-based TTA upconversion.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.