Lithographically defined nano-morphology in polymer-fullerene solar cells towards high efficiency

本研究的目的是开发一种垂直双连续的供体和受体材料相互穿透的最佳形态，以实现有机太阳能电池的高效率。这种形态使吸收深度与扩散长度脱钩，允许有效的激子扩散到大的界面区域，以及减少复合的垂直电荷传输。知识优势：提出的纳米压印光刻技术与创新的模具技术提供了一个实用的手段，更高的精度比目前可用的技术，使一个最佳的太阳能电池设计。热印迹工艺还可以诱导良好的聚合物链排列和结晶，导致更高的空穴迁移率和光吸收。通过将吸收深度与扩散长度解耦，可以使用比传统体异质结器件更厚的聚合物膜来显著增强光吸附。这种形态提供了一个基本的纳米平台来研究相关的聚合物性质（结晶度、迁移率、链取向、稳定性、热动力学性质等）及其与几何形状、压印温度、表面效应和器件量子效率的关系。更广泛的影响：本研究将建立对异质结纳米形态对材料性能和器件特性的影响的全面理解，这对其他材料和器件具有变革意义。接下来可能会出现聚合物太阳能电池中7-12% PCE的演示。这项研究将通过UTD现有的课程与教育相结合，为学生提供研究机会。特别是，该计划旨在为包括本科生和整个教育界在内的广泛个人带来更多的纳米技术接触。

The objective of this research is to develop an optimal morphology of vertically bi-continuous donor and acceptor materials interpenetrating into each other to achieve high efficiency in organic solar cells. This morphology decouples absorption depth from diffusion length, allowing effective exciton diffusion to large interfacial areas as well as vertical charge transport with reduced recombination. Intellectual merit: The proposed nanoimprint lithography with innovative mold technologies provides a practical means with greater precision than currently available techniques to make an optimal solar cell design. The thermal imprinting process can also induce favorable polymer chain alignment and crystallization, leading to higher hole mobility and light absorption. By decoupling absorption depth from diffusion length, a thicker polymer film than in conventional bulk heterojunction devices can be used to enhance light adsorption considerably. This morphology provides a basic nano-platform to study the interrelated polymer properties (crystallinity, mobility, chain orientation, stability, thermal dynamic properties, etc) and their correlation with geometry, imprint temperature, surface effects, and device quantum efficiency. Broader impacts: This study will establish a comprehensive understanding of the effects of heterojunction nano-morphology on material properties and device characteristics, which is transformative to other materials and devices. What may naturally follow is the demonstration of 7-12% PCE in polymer solar cells. This research will be integrated with education through available programs at UTD to provide research opportunities for students. Particularly, this program aims to bring greater nanotechnology exposure to a broad range of individuals including undergraduates and the education community on the whole.