EAGER: Novel Interfaces for Nanostructured Solar Cells

染料敏化太阳能电池（DSSC）是一种很有前途的低成本太阳能转换技术，其中，吸附在半导体上的染料分子吸收光，向半导体注入光注入电子（被氧化），并被溶解的碘化物还原（再生），得到中性染料和三碘化物。电子从半导体中收集，通过外部电路，并返回到对电极，在那里它将三碘化物还原为碘化物，完成电路。碘化物还原氧化染料需要很大的过电位（至少0.5 V），这在DSSC中构成了显著的能量损失。可选择的氧化还原偶可以用更小的过电位还原氧化染料，倾向于以高速率从半导体中去除电子，用另一种损失过程取代一种损失过程。克服后一个问题（重组）需要提高半导体中电子传输的速度，以便在电子在重组中丢失之前将其提取出来。这个探索性项目将产生初步的数据，以证明新的复合半导体纳米结构解决这个问题的潜力。主导这项工作的设计范例是两种半导体材料的配对：染料分子吸附和注入电子的活性层，以及从活性层中提取电荷并迅速将其传输到导电衬底以进行收集的传输层。活性层必须具有高表面积，以允许每个几何面积的大染料负载，以强吸收入射阳光。这一范式的两个实例将在本工作中产生。一种是将二氧化钛纳米粒子包覆在氧化锌纳米棒上；纳米棒提供快速运输，而纳米颗粒大大增加了总表面积。另一种是在掺氟氧化锡（FTO）气凝胶上的一层二氧化钛共形层。气凝胶本质上是一个高表面积结构，允许活性层的保形涂层。该项目侧重于关于阻碍复合的阻挡层的初步数据，FTO气凝胶样品中氟掺杂水平的分析，以及用新型复合半导体薄膜制成的太阳能电池器件的光电测量。更广泛的影响本研究将显著推进低成本太阳能转换技术，面对大量人口急剧增加的能源使用以及迫在眉睫的气候变化和化石燃料燃烧带来的其他环境影响，这一技术越来越迫切需要。该项目将为参与的研究生提供教育和培训，包括撰写研究文章和前往国内和国际会议传播研究成果。PI积极吸引K-12学生和教师使用DSSC作为与能源，环境，化学和工程相关主题的教学工具。

The dye-sensitized solar cell (DSSC) is a promising technology for low-cost solar energy conversion in which a dye molecule adsorbed on a semiconductor absorbs light, injects a photoinjected electron into the semiconductor (becoming oxidized), and is reduced (regenerated) by dissolved iodide, giving the neutral dye and triiodide. The electron is collected from the semiconductor, travels through an external circuit, and is returned to a counterelectrode where it reduces triiodide to iodide, completing the circuit. The reduction of oxidized dyes by iodide requires a large overpotential (at least 0.5 V), constituting a significant energy loss in the DSSC. Alternative redox couples that can reduce oxidized dyes with much smaller overpotentials tend to remove electrons from the semiconductor at high rates, replacing one loss process with another. Surmounting this latter problem (recombination) requires increasing the speed of electron transport in the semiconductor, in order that the electron may be extracted before it is lost to recombination. This exploratory project will generate preliminary data to demonstrate the potential for new composite semiconductor nanostructures to solve this problem.Intellectual MeritThe design paradigm that governs this work is the paring of two semiconducting materials:an active layer on which dye molecules adsorb and inject electrons, and a transport layer that extracts charges from the active layer and rapidly transports them to the conducting substrate for collection. The active layer must have a high surface area to allow a large dye loading per geometric area for strong absorption of incident sunlight. Two instances of this paradigm will be produced in this work. One consists of titania nanoparticles coated over zinc oxide nanorods; the nanorods provide fast transport while the nanoparticles greatly increase the total surface area. The other is a conformal layer of titania over a fluorine-doped tin oxide (FTO) aerogel. The aerogel is inherently a high-surface area structure, allowing a conformal coating of the active layer. This project focuses on preliminary data regarding blocking layers to retard recombination, analysis of fluorine dopant levels in FTO aerogel samples, and optoelectronic measurements of solar cell devices made with the novel composite semiconductor films.Broader ImpactsThis research will significantly advance the technology of low-cost solar energy conversion, for which there is an increasingly urgent need in the face of sharply increasing energy usage among a large population together with impending climate change and other environmental impacts from fossil fuel combustion. The project will provide education and training to involved graduate students including the writing of research articles and travel to domestic and international conferences for dissemination of the results. The PI actively engages K-12 students and teachers using the DSSC as a teaching tool for topics related to energy, the environment, chemistry and engineering.