CAREER: Scalable Electrospray Processing of High-Efficiency Perovskite Solar Cells

这项学院早期职业发展(Career)计划旨在通过电喷沉积在制造高效薄膜太阳能电池方面开辟新的天地。目前，几乎所有的商业薄膜太阳能电池都涉及昂贵的真空环境和稀土材料，而这些材料的供应有限。为了帮助降低制造成本，缓解国家对稀土元素的依赖，该奖项支持基于解决方案的太阳能电池制造工艺的基础研究，该工艺在大气压下运行，只使用钙钛矿等富含地球的材料。钙钛矿型太阳能电池的功率转换能超过15%，高于最好的有机太阳能电池，有接近30%的潜力。所产生的知识将使柔性薄膜(300 Nm)太阳能电池的可扩展、卷到卷制造工艺成为可能。该工艺使用由静电液体雾化技术产生的极细的喷雾，在衬底上覆盖一层薄而均匀的液膜。液膜的干燥将受到司法控制，以提高固化薄膜的质量，提高功率转换效率。这项研究项目横跨多个学科，如制造、热流体科学和材料科学。太阳能的广泛吸引力提供了一个极好的教育机会，可以提高公众的科学素养，让女性和其他未被充分代表的学生群体参与到物理学中来，并更好地为学生为现代劳动力做出贡献做好准备。多晶钙钛矿太阳能电池迅速成为高效太阳能转换设备的有力竞争者，因为钙钛矿型光伏材料储量丰富，价格低廉，可以在中等温度和大气压下加工。这些宽松的工艺条件扩大了兼容基板的选择范围，从而使串联太阳能电池和卷到卷制造等技术成为可能。然而，仍然存在两大挑战。首先，液体薄膜在干燥过程中容易破裂和脱湿，留下很大一部分衬底区域未被覆盖。其次，超薄(300 Nm)钙钛矿薄膜的可扩展制造工艺仍然缺乏。这项拟议的研究承担了薄膜破裂和制造可伸缩性的双重挑战。提出了控制液体薄膜干燥的思想，以抑制湿薄膜的自发破裂，减少有害针孔的形成，改善晶体结构，从而提高功率转换效率。研究小组将制定一个理论模型，规定抑制薄膜破裂的流体、机械和热边界。模型预测将与调节干燥实验进行比较和验证，随后将进行薄膜表征和设备性能评估，以揭示工艺、特性和性能之间的相互影响。

This Faculty Early Career Development (CAREER) Program grant aims to break new ground in the manufacturing of high-efficiency thin-film solar cells through electrospray deposition. Presently, nearly all commercial thin-film solar cells involve costly vacuum environments and rare earth materials, which are in limited supply. To help reduce the manufacturing cost and ease the nation's dependence on rare earth elements, this award supports fundamental research on a solution-based solar cell manufacturing process that operates at atmosphere pressure and uses only earth-abundant materials such as perovskites. Perovskite solar cells have exhibited power conversion energies above 15 percent, which is higher than the best organic solar cells, and have the potential of approaching 30 percent. The knowledge generated will enable a scalable, roll-to-roll manufacturing process of flexible thin-film (300 nm) solar cells. The process uses extremely fine spray generated by an electrostatic liquid atomization technique to coat a substrate with a thin and uniform layer of liquid film. The drying of the liquid film will be judicially controlled to enhance the quality of the solidified thin-film and boost the power conversion efficiency. This research project crosscuts multiple disciplines such as manufacturing, thermo-fluid science, and materials science. The broad appeal of solar energy renders an excellent educational opportunity to increase public scientific literacy, engage women and other underrepresented student groups in physical sciences, and better prepare students to contribute to a modern workforce.Polycrystalline perovskite solar cells have rapidly emerged as strong contenders for efficient solar energy conversion devices because perovskite photovoltaic materials are earth abundant, inexpensive, and can be processed at moderate temperatures and atmospheric pressure. These relaxed processing conditions expand the selection of compatible substrates thereby enabling technologies such as tandem solar cells and roll-to-roll fabrication. However, two major challenges remain. First, the liquid films tend to rupture and de-wet during drying, leaving significant portion of substrate area uncovered. Second, scalable manufacturing processes for ultra-thin (300 nm) perovskite films are still lacking. The proposed research undertakes the dual challenges of film rupture and manufacturing scalability. The idea of regulated drying of thin liquid films is proposed to suppress spontaneous rupture of the wet film, reduce detrimental pin-hole formation, improve crystal structure and, consequently, increase the power conversion efficiency. The research team will formulate a theoretical model to prescribe fluid mechanical and thermal boundaries that suppress film rupture. Model predictions will be compared and validated with experiments on regulated drying, followed by film characterization and device performance evaluation to reveal the interplay between processing, characteristics and performance.