High-Efficiency Dye-Sensitized Solar Cells Based on Ordered TiO2 Nanotube Arrays

0967722高光敏化太阳能电池（dsc）具有低成本太阳能发电的潜力。目前的dsc阳极采用TiO2纳米颗粒烧结的介孔膜。虽然这种薄膜的无序孔隙结构为染料吸附提供了很高的比表面积，但这些材料的电子寿命短，电子传递途径长，限制了dsc太阳能转换效率的提高。基于有序ZnO纳米线的阳极有望克服这些限制。然而，作为DSC光阳极，ZnO材料的性能不如TiO2。以前通过阳极氧化大块钛来制造TiO2纳米管光阳极的尝试产生了不透明的薄膜，这需要背面照明配置，导致近20%的入射光子损失。该研究将使用一种简单的方法直接在透明导电氧化物（TCO）表面合成垂直排列的TiO2纳米管阵列。由于TiO2纳米管中的电子寿命比ZnO纳米线或烧结TiO2纳米颗粒中的电子寿命长十倍以上，因此用这些TiO2纳米管制备的dsc具有显著优于基于ZnO纳米线的器件的潜力。该研究将利用有序TiO2纳米管阵列光电阳极显著延长的电子寿命和提高的可及性来开发高效的dsc。这种配置也将有助于使用固态电解质来克服基于液体电解质的dsc的封装挑战。拟议的研究有五个目标。第一个目标是直接在TCO上合成超长有序TiO2纳米管阵列。第二个目标是通过超长有序TiO2纳米管阵列制备具有增厚敏化膜的dsc。剩下的目标是探索dsc中的替代氧化还原介质，用固态电解质制备TiO2纳米管dsc，并用量子点敏化dsc。这项研究具有潜在的变革性，因为它提供了一种新的方法，可以从根本上改进电荷传输，从而突破DSC器件的效率障碍。更广泛的影响建议开展三项教育和外展活动。第一项活动是通过实践研究培养研究生和本科生。第二项活动侧重于为本科生开发一个国际实地研究模块，通过与中国清华大学的合作，为可持续工程提供国际视角。第三项活动的重点是通过1)开发“可持续发展与创新”高中课程单元，以及2)与宾夕法尼亚州匹兹堡的鲍德温高中和西屋高中合作，开展实践科学研讨会，向少数民族大学预科学生提供服务。

0967722GaoDye-sensitized solar cells (DSCs) have potential for low-cost solar electricity production. Anodes of current DSCs use sintered mesoporous films of TiO2 nanoparticles. Although the disordered pore structure of such films provides a high surface area for dye adsorption, the short electron lifetime and long pathway electron transport in these materials have limited the improvement of the solar energy conversion efficiency of DSCs. Anodes based on ordered ZnO nanowires have shown promise to overcome these constraints. However, ZnO material properties are not as good as TiO2 for DSC photoanodes. Previous attempts at fabricating TiO2 nanotube photoanodes by anodizing bulk titanium produced opaque films, which required a backside illumination configuration and resulted in nearly 20% of incident photon loss. Intellectual MeritThe proposed research will use a facile method for synthesis of vertically-aligned TiO2 nanotube arrays directly on transparent conductive oxide (TCO) surfaces. DSCs fabricated with these TiO2 nanotubes have to potential to significantly outperform ZnO nanowire-based devices, because the electron lifetime in TiO2 nanotubes is more than ten times longer than that either in ZnO nanowires or in sintered TiO2 nanoparticles. The proposed research will take advantage of the significantly extended electron lifetime and improved accessibility of ordered TiO2 nanotube array photoanodes to develop high efficiency DSCs. This configuration will also facilitate the use of a solid-state electrolyte to overcome the packaging challenges with liquid electrolyte based DSCs. The proposed research has five objectives. The first objective is to synthesize ultra-long ordered TiO2 nanotube arrays directly on TCO. The second objective is to fabricate DSCs with thickened sensitized films enabled by the ultra-long ordered TiO2 nanotube arrays. The remaining objectives are to explore alternative redox mediators in DSCs, fabricate TiO2 nanotube DSCs with a solid-state electrolyte, and sensitize DSCs with quantum dots. The research is potentially transformative because it provides a new approach to make the fundamental improvements in charge transport needed to break through the efficiency barriers of DSC devices. Broader ImpactsThree education and outreach activities are proposed. The first activity is the training graduate and undergraduate students through hands-on research. The second activity focuses on the development of an international field study module for undergraduate students that provides an international perspective to sustainable engineering through a collaboration with Tsinghua University in China. The third activity focuses on outreach to minority pre-college students through 1) development of high-school course unit on "Sustainability and Innovation", and 2) hands-on science workshops in collaboration with Baldwin High School and Westinghouse High School in Pittsburgh, PA.