Enhancement of Exciton Dissociation in Organic Solar Cells

技术上的。该项目旨在更好地了解和提高有机太阳能电池中激子离解率的能力，并总体上准确地确定单个有机/有机和有机/无机界面上的离解电荷比例。长期目标是，通过更全面地了解激子解离过程，开发一种策略，将有机太阳能电池的效率提高到更接近无机材料的水平。自旋过滤材料和重金属自旋轨道耦合器将被用来诱导光耦合到三重态激子态，从而将吸收光谱扩展到近红外。吸收到三重态将给出单态/三重态间距的直接测量，而三重态激子态的解离将提供相对于单态解离速率的三重态。自旋-轨道耦合强度将被确定为磁化强度和自旋取向的函数。此外，结合压电聚合物将被用来创造一个内置的电场，从而改变激子光谱。这有望将吸收转移到红外线，或提高光激发载流子的捕获效率。电荷离解过程将使用电容光电流技术来测量，该技术结合激发电荷的物理分离来检测光吸收。这提供了区分激子和自由载流子状态、确定激子结合能和复合效率以及界面材料和条件对激子形成和解离的影响的能力。非技术性。该项目涉及具有技术相关性的电子/光子材料科学专题领域的基础研究问题。这项研究有可能对改进的、更便宜的太阳能电池的开发产生重大影响。这项研究提供了对有机材料中激子有效解离必要条件的更多了解，这可能为开发低成本、商业可行的有机太阳能电池技术开辟一条道路。正在为研究生、本科生和高中生提供研究机会，重点是招募女性和其他代表性不足的群体。一门关于先进设备概念的新本科课程正在推出，其中将包括这里提出的研究策略。将向当地高中教师介绍研究，并对他们进行实验技术培训，以便他们能够开发研究模块，向学生展示。这个想法是为了让高中生接触到能源转换科学的兴奋，并鼓励他们追求科学和工程方面的职业。

Technical. The project aims for greater understanding of, and the ability to enhance, the exciton dissociation rate in organic solar cells, and generally, to accurately determine the fraction of dissociated charge across individual organic/organic and organic/inorganic interfaces. The long-term goal is, through more complete understanding of the exciton dissociation process, to develop a strategy for improving organic solar cell efficiency to levels closer to that achieved in inorganic materials. Spin filtering materials and heavy metal spin orbit couplers will be used to induce optical coupling into triplet excitonic states, thereby expanding the absorption spectrum into the near infrared. Absorption into the triplet state will give a direct measurement of singlet/triplet spacing, while dissociation of triplet exciton states will provide the relative triplet to singlet dissociation rate. Spin-orbit coupling strengths will be determined as a function of magnetization and spin orientation. Additionally, incorporation of piezoelectric polymers will be used to create a built-in electric field, and thereby alter the excitonic spectrum. This is expected to shift the absorption to the infra-red, or increase the capture efficiency of the photo-excited carriers. The charge dissociation process will be measured using a capacitive photocurrent technique that detects optical absorption combined with physical separation of excited charge. This provides the ability to distinguish between excitonic and free carrier states, to determine excitonic binding energies and recombination efficiencies and the influence of interface materials and conditions on exciton formation and dissociation. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having technological relevance. There is potential that the research could substantially impact the development of improved and less expensive solar cells. The increased understanding of the conditions necessary for efficient exciton dissociation in organic materials provided by this study may establish a pathway for developing a low-cost, commercially viable organic solar cell technology. Research opportunities are being provided for graduate, undergraduate, and high school students with an emphasis on recruiting women and other under-represented groups. A new undergraduate course on advance device concepts is being introduced, and will include the research strategies being proposed here. Local high school teachers will be introduced to research and trained in experimental techniques so that they will be able to develop research modules to present to their students. The idea is to introduce high school students to the excitement of energy conversion science, and encourage them to pursue careers in science and engineering.