Structure and Process Engineering Facilitated by PAMAM Dendrimers for Highly Stable Perovskite Solar Cells

尽管在效率方面取得了巨大进步，但钙钛矿型太阳能电池仍必须克服一些重大问题，才能在光伏市场上具有经济竞争力。钙钛矿型太阳能电池商业化的主要障碍是寿命短和制造时间长。在这个项目中，短寿命和制造问题将通过一种由特定聚合物材料聚酰胺胺(PAMAM)树枝状大分子实现的新型工艺和器件结构工程来解决，同时保持效率。这项研究的提出不仅将促进太阳能电池制造领域的知识进步，而且将对社会产生影响。教育目标是促进太阳能电池先进制造的STEM教育。通过这一项目，将雇用代表性不足的少数群体和女性学生从事拟议的研究，并将研究成果纳入教学课程。作为外展活动，将在阿拉巴马州黑带地区的中学开发和演示太阳能电池科学模块，鼓励更多的少数民族学生在大学学习中进入STEM领域。钙钛矿型太阳能电池(PVSCs)存在不稳定性，寿命短。这些类型的太阳能电池的加工还需要较长的退火期和多个沉积步骤。在这个项目中，器件的不稳定性将从有源层和电荷传输层两个方面来解决。通过在钙钛矿活性层中加入特定的聚合物，将获得一种凝聚的钙钛矿膜，它将防止水分和氧气的渗透，从而显著提高稳定性。器件结构工程将基于传统的倒置平面结构，以无机金属氧化物为电子传输层，去除空穴传输层。由于PAMAM树枝状大分子的加入，确保了钙钛矿/ITO界面良好的粘附性和耐水性，防止了水从ITO侧扩散到钙钛矿型吸收材料中。ITO功函数将通过化学处理而增加，作为一个“看不见的”空穴传输层，帮助收集空穴并阻止钙钛矿/ITO界面的电子传输。因此，这种结构工程方法不仅可以提高稳定性，还可以保持高功率转换效率(PCE)的前景。为了加深对PAMAM树枝状大分子添加的基本了解，我们将用透射电子显微镜(TEM)表征聚合物添加剂在钙钛矿型薄膜中的分布，并对未添加聚合物和具有最佳聚合物含量的样品进行缺陷、复合和载流子寿命的原位表征。此外，还将在聚合物镀膜玻璃上溅射得到超光滑的ITO薄膜。提高了ITO表面两侧聚合物的耐磨性，提高了器件的可靠性。在整个研究过程中，所有的钙钛矿太阳能电池叠层都将经过快速光子退火和烧结，为通过低成本、高速打印大规模生产钙钛矿太阳能电池组件铺平道路。这一奖项反映了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。

Despite dramatic progress in efficiency, perovskite solar cells still must overcome some major problems before becoming economically competitive in the photovoltaic market. The main obstacles for commercialization of perovskite solar cells are short lifespan and long fabrication time. In this project, the short lifespan and manufacturing issues will be addressed through a novel process and device structure engineering enabled by a specific polymer material, polyamidoamine (PAMAM) dendrimers, while maintaining the efficiency. The proposed research will not only advance the knowledge in solar cell fabrication, but also impact society. The educational goal is to promote STEM education on advanced manufacturing of solar cells. Through this project, under-represented minority and female students will be hired to work on the proposed research, and research outcomes will be integrated in the teaching courses. As outreach activities, scientific modules on solar cells will be developed and demonstrated in the middle schools of the Black Belt region of Alabama, encouraging more minority students to enter STEM fields in their college study. Perovskite solar cells (PVSCs) suffer from instability, which leads to short lifetimes. The processing of these types of solar cells also requires long annealing times, and multiple deposition steps. In this project, device instability will be addressed from both active layer and charge transporting layers. With the incorporation of a specific polymer into the perovskite active layer, a condensed perovskite film will be attained, which will prevent penetration of moisture and oxygen, leading to significant improvement in stability. Device structure engineering will be based on the conventional inverted planar architecture with inorganic metal oxide as electron transporting layer and removal of hole transport layer. Because of the addition of PAMAM dendrimers, good adhesion and water resistance are ensured at the perovskite/ITO interface, precluding water diffusion into the perovskite absorber from the ITO side. The ITO work function will be increased through a chemical treatment, serving as an “invisible” hole transport layer to assist hole collection and block electron transport at the perovskite/ITO interface. Therefore, this structure engineering approach will not only enhance stability, but also maintain the promise of high power-conversion efficiency (PCE). To advance fundamental understanding on addition of PAMAM dendrimers, distribution of polymer additives in perovskite thin films will be characterized with Transmission Electron Microscopy (TEM), and in-situ characterization of defects, recombination, and carrier lifetime will be conducted for samples without polymer addition and with optimal polymer loading. In addition, an ultra-smooth ITO film will be attained through sputtering on polymer coated glass. The increase of rob-off resistance from the polymer on both sides of the ITO surfaces improves device reliability. Throughout this study, all the stacking layers of perovskite solar cells will go through rapid photonic annealing and sintering, paving the way for mass production of perovskite solar modules through low-cost, high-speed printing.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.