Nitrogen-doped and CdSe quantum-dot-sensitized nanocrystalline TiO2 films for solar energy conversion applications
Nitrogen-doped and CdSe quantum-dot-sensitized nanocrystalline TiO2 films for solar energy conversion applications
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DOI：
10.1021/jp077345p
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发表时间：
2008-01-31
影响因子：
3.7
通讯作者：
Zhang, Jin Z.
中科院分区：
文献类型：
--
作者：
Lopez-Luke, Tzarara;Wolcott, Abraham;Zhang, Jin Z.
以六次甲基四胺（HMT）为掺杂源，采用溶胶-凝胶法制备了氮掺杂二氧化钛（TiO 2/N）纳米颗粒薄膜。合成的TiO 2/N薄膜已经敏化与CdSe量子点（QD）通过连接分子，巯基乙酸（TGA）。通过AFM、TEM、XPS、拉曼光谱、紫外-可见光谱和光电化学技术对具有和不具有QD敏化的薄膜的光学、形态、结构和光电流性质进行了表征。原子力显微镜测量表明，薄膜的厚度为150和1100 nm，可以很容易地。制备，具有100 nm的平均TiO 2粒度。TEM显示用于敏化TiO 2/N膜的CdSe量子点的均匀尺寸分布。通过XPS确认了通过HMT对TiO 2晶格的掺杂为0.6-0.8%。使用XRD和拉曼光谱阐明了由前体HMT、硝酸和聚乙二醇（PEG）引起的晶相差异。所得的TiO 2/N的晶相变化，但为金红石、板钛矿和金红石相的混合物。紫外-可见吸收光谱表明，N掺杂的TiO 2引起红移到可见光区的吸收，与约600 nm的开始。氮掺杂也是负责增强的光电流响应的TiO 2/N纳米粒子薄膜在可见光区相对于未掺杂的TiO 2薄膜。此外，CdSe量子点连接到TiO 2/N纳米粒子使用TGA被发现显着增加的光电流和功率转换的薄膜相比，标准TiO 2/N薄膜没有量子点敏化。在Na 2S电解液中，TiO 2/N-TGA-CdSe固态太阳能电池在400 nm处的入射光-电流转换效率（IPCE）为6%，而TiO 2/N-TGA-CdSe薄膜在300 nm处的入射光-电流转换效率为95%，远高于未掺杂的QD敏化TiO 2和未掺杂的QD敏化TiO 2/N。对于1100 nm厚的TiO 2/N-TGA-CdSe薄膜，功率转换效率（q）为0.84%，填充因子（FF%）为27.7%。结果表明，氮掺杂与量子点敏化相结合是提高TiO 2薄膜在近紫外和可见光区光响应的有效途径，对潜在的光伏（PV）和光电化学应用具有重要意义。
Nitrogen-doped titanium dioxide (TiO2/N) nanoparticle thin films have been produced by a sol-gel method with hexamethylenetetramine (HMT) as the dopant source. The synthesized TiO2/N thin films have been sensitized with CdSe quantum dots (QDs) via a linking molecule, thioglycolic acid (TGA). Optical, morphological, structural, and photocurrent properties of the thin films with and without QD sensitization have been characterized by AFM, TEM, XPS, Raman spectroscopy, UV-visible spectroscopy, and photoelectrochemistry techniques. AFM measurements reveals that films with thicknesses of 150 and 1100 nm can be readily. prepared, with an average TiO2 particle size of 100 nm. TEM shows a uniform size distribution of CdSe QDs utilized in sensitizing the TiO2/N films. Doping of the TiO2 crystal lattice by HMT was confirmed to be 0.6-0.8% by XPS. Differences in crystal phase caused by the precursors HMT, nitric acid, and poly(ethylene glycol) (PEG) are elucidated using XRD and Raman spectroscopy. The resultant crystal phase of TiO2/N varies but is a mixture of anatase, brookite, and rutile phases. UV-visible absorption spectra show that N doping of TiO2 causes a red-shifted absorption into the visible region, with an onset around 600 nm. Nitrogen doping is also responsible for the enhanced photocurrent response of the TiO2/N nanoparticle films in the visible region relative to undoped TiO2 films. In addition, CdSe QDs linked to TiO2/N nanoparticles using TGA were found to significantly increase the photocurrent and power conversion of the films compared to standard TiO2/N films without QD sensitization. The incident photon-to-current conversion efficiency (IPCE) is 6% at 400 nm for TiO2/N-TGA-CdSe solid-state solar cells and 95% for TiO2/N-TGA-CdSe films near 300 nm in a Na2S electrolyte, which is much higher than that of undoped TiO2 With QD sensitization or TiO2/N without QD sensitization. The power conversion efficiency (q) was found to be 0.84% with a fill factor (FF%) of 27.7% with 1100 nm thick TiO2/N-TGA-CdSe thin films. The results show that combining nitrogen doping with the QD sensitization of TiO2 thin films is an effective and promising way to enhance the photoresponse in the near-UV and visible region, which is important for potential photovoltaic (PV) and photoelectrochemical applications.