Collaborative Proposal: Fundamental Research on Physics of Instability of Organic Solar Cells

PI：Dalal，Vikram/Schiff，EricProposal Numbers：1336134/1336147机构：爱荷华州立大学/锡拉丘兹大学标题：合作提案：有机太阳能电池不稳定性物理学基础研究这个项目将系统地研究、识别并有可能克服材料和器件中导致有机太阳能电池受光时退化的各种物理现象。有机光伏(OPV)器件是一种日益重要的光伏(PV)能量转换技术。最近，单结和串联结OPV太阳能电池的效率都达到了~12%的范围，这对最终的商业部署非常令人鼓舞。然而，众所周知，这些设备在暴露在光线下时会迅速降解，即使是在密封或保持在惰性大气中的情况下，也会在~100小时内损失20-30%的初始效率。这项技术的一个主要市场是建筑集成产品，因为原则上，OPV设备可以层叠到现有的窗框上。对于这种商业部署，至关重要的是在产品的生命周期内将降解率显著降低到10%，对于建筑产品来说，这通常是~20年。同样，为发展中国家的农村人口提供电力的另一个主要细分市场也需要相对较长的寿命，尽管它们不需要与美国并网中央电源相同的电力转换效率。该项目将系统地研究OPV材料和设备在照明时吸收材料和异质结界面的基本物理参数的变化，如光吸收、空穴迁移率、深态密度。PI将使用不同温度下的电学测量(如电容-频率)和结构测量(如自旋共振)来研究缺陷的演变。PIS将研究在不同光强下缺陷随时间演化的动力学，以建立支配缺陷演化的动力学规律。然后，PI将随着时间的推移系统地探索这些缺陷的热退火，从而找出退火的激活能。PI将这些动力学和退火能与有机材料的结构、形态和组成以及用于制造器件的特定技术相关联。将研究一些不同的材料，如P3HT和PCDTBT，并建立各种动力学参数与材料中键的性质之间的关系。我们将利用这些结果来设计和制造更好的聚合物，这些聚合物可能更稳定，同时保持电力转换效率。更广泛的影响包括工作的工业影响，以及在OPV设备和材料领域的研究生和本科生的教育，特别是在一般的太阳能转换设备领域。将非常重视将研究成果转化为教育，在现有课程中增加新的实验部分。预计女性和代表性不足的少数群体学生都将在这项研究中发挥重要作用。研究结果将通过出版物和通过IEEE提供的网络研讨会向科学家和工程师广泛传播。将通过在美国和海外的演讲向普通公众传播。

PI: Dalal, Vikram / Schiff, EricProposal Number: 1336134 / 1336147Institution: Iowa State University / Syracuse UniversityTitle: Collaborative Proposal: Fundamental Research on Physics of Instability of Organic Solar CellsThis project will to systematically study, identify, and potentially overcome the various physical phenomena in both materials and in devices that lead to degradation of organic solar cells when subjected to light. Organic photovoltaic (OPV) devices are an increasingly important photovoltaic (PV) energy conversion technology. Recent advances in efficiency to ~12% range in both single and tandem junction OPV solar cells are very encouraging for eventual commercial deployment. However, the devices are known to degrade rapidly when exposed to light, losing 20-30% of the initial efficiency within ~100 hours of illumination, even when encapsulated or kept in inert atmospheres. A major market for this technology is building-integrated products, since in principle, the OPV devices can be laminated onto existing window frames. For such commercial deployment, it is essential that the degradation be reduced significantly, to 10% range over the lifetime of the product, which is typically ~20 years for building products. Similarly, another major market segment, providing power for rural populations in developing countries, also requires relatively long life, even though they do not require the same power conversion efficiency as grid-connected central power in the U.S. This project will systematically investigate the changes in fundamental physical parameters such as optical absorption, hole mobility, deep state densities in both the absorber materials and at the hetero-junction interface when OPV materials and devices are subjected to illumination. The PIs will study the evolution of defects using both electrical measurements such as capacitance-frequency at different temperatures, and structural measurements such as spin resonance. PIs will study the kinetics of defect evolution over time under varying intensities of light so as to establish kinetic laws that govern defect evolution. Then, the PIs will systematically explore the thermal annealing of these defects over time, thereby finding out activation energies for annealing. The PIs will correlate these kinetics and annealing energies to the structure, morphology and composition of the organic materials, and the specific technology used for fabricating the devices. A number of different materials such as P3HT and PCDTBT will be studied and the relationship between the various kinetic parameters to the nature of the bonding in the materials will be established. We will use these results to design and fabricate better polymers which are likely to be more stable while maintaining power conversion efficiency. The broader impact consists of the industrial impact of the work, and in educating both graduate and undergraduate students in the field of OPV devices and materials in particular, and solar energy conversion devices in general. Significant attention will be paid to transfer the research results into education by including new lab sections in existing courses. Both women and under-represented minority group students are expected to play a significant role in the research. The results of the research will be broadly disseminated to scientists and engineers through publications, and by offering webinars through IEEE. Dissemination to the general public will be done by giving talks both in the U.S. and overseas.