Department of Electrical and Computer Engineering and Nano Tech Center, Texas Tech University, Lubbock, TX 79409-3102, USA.
Nanotechnology. 2011 Jun 10;22(23):235402. doi: 10.1088/0957-4484/22/23/235402. Epub 2011 Apr 7.
We present a detailed study of the infiltration of titanium dioxide (TiO(2)) nanotubes (NTs) with TiO(2) nanoparticles (NPs) for dye sensitized solar cells (DSSCs). The aim is to combine the merits of the NP's high dye loading and high light harvesting capability with the NT's straight carrier transport path and high electron collection efficiency to improve the DSSC performance. On infiltrating NTs with TiCl(4) solution followed by hydrothermal synthesis, 10 nm size NPs were observed to form a conformal and dense layer on the NT walls. Compared with the bare NT structure, dye loading of this mixed NT and NP structure is more than doubled. The overall photon conversion efficiencies of the fabricated DSSCs are improved by 152%, 107%, and 49% for 8, 13, and 20 µm long NTs, respectively. Electron transport and recombination parameters were extracted based on electrochemical impedance spectroscopy measurements. Although a slight reduction of electron lifetime was observed in the mixed structures due to enhanced recombination with a larger surface area, the diffusion length is still significantly longer than the NT length used, suggesting that most electrons are collected. In addition to dye loading and hence photocurrent increment, the photovoltage and filling factor were also improved in the mixed structure due to a low serial resistance, leading to the enhancement of the overall efficiency.
我们对二氧化钛（TiO(2)）纳米管（NTs）进行了详细的研究，以将 TiO(2)纳米粒子（NPs）渗透到染料敏化太阳能电池（DSSCs）中。目的是将 NP 的高染料负载和高光捕获能力与 NT 的直载流子传输路径和高电子收集效率相结合，以提高 DSSC 的性能。在将 NT 用 TiCl(4)溶液渗透后进行水热合成，观察到 10nm 大小的 NPs 在 NT 壁上形成了一个一致和致密的层。与裸 NT 结构相比，这种混合 NT 和 NP 结构的染料负载增加了一倍以上。制造的 DSSC 的整体光子转换效率分别提高了 152%、107%和 49%，对于 8 µm、13 µm 和 20 µm 长的 NT。基于电化学阻抗谱测量，提取了电子传输和复合参数。尽管由于表面积增大而导致复合增强，混合结构中的电子寿命略有降低，但扩散长度仍然明显长于使用的 NT 长度，表明大多数电子被收集。除了由于光电流增加导致的染料负载增加外，由于低串联电阻，混合结构中的光电压和填充因子也得到了改善，从而提高了整体效率。
