Formation of photo-thermoelectric energy conversion functional films by controlling film structure in nanometer scale.

通过纳米尺度控制薄膜结构形成光热电能量转换功能薄膜。

• 批准号: 10650649
• 负责人: ISHIGURO Takashi
• 金额: $ 2.18万
• 依托单位: Nagaoka University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650649/
• 关键词: thermoelectric materials; functionally graded films; solar energy absorption film; mesoscopic structire; Seebeck coefficient; ultrafine particle; surface plasmon; energy conversion film; 金属超微粒子; 光熱変換; メゾスコピック材料

In order to exploit solar energy resources, the photo-thermoelectric energy conversion functional films have been investigated. The subject has been composed of two functional parts, I.e., (1) : photo-thermal energy conversion films and (2) : thermoelectric energy conversion films. The aim of the investigation is to improve individual function by forming the suitable mesoscopic structure in the films.(1) Ag/MgO and/or W-N/AlN multi-layer sutuctured films are formed by the sputtering method. With increasing Ag layer thickness, the optical properties change from the surface-plasmon absorption due to fine particle into bulk metallic property via conductive absorption which shows relatively large absorbance in the near infrared region as well as visible light region. The functionally graded Ag/MgO film is formed based on the above results. Then the total solar energy absorbance of 87% is achieved. The same procedure is performed on the W-N/AlN system. The finally obtained functionally graded W-N/AlN film shows a total solar energy absorbance of 93%.(2) Sputtered Fe-Si films are annealed (853K x 2h) in a vacuum. The change of the electrical resistivity (ρ) and the Seebeck coefficient (α) are measured. The film with a composition of FeSiィイD22ィエD2 shows maximum values of ρ and α. The multi-layered FeSiィイD22ィエD2/C films are formed. The value of ρ is successfully reduced but the α is also reduced. The power factor is not improved consequently. The sputtered Co-Sb films are also formed. By annealing, the amorphous-structured films change into polycrystalline structure including high-density voids with nanometer size. Such a nano-void structure may contribute to the reduction of thermal conductivity.It has been presented in this research that the introduction of the suitable mesoscopic structures into the intrinsic film structure is effective to improve the inherent function. The performing the optimization will be a future problem.

为了开发太阳能资源，人们对光电热电转换功能薄膜进行了研究。本课题由两个功能部分组成，即(1)：光热转换膜和(2)：热电转换膜。研究的目的是通过在薄膜中形成合适的介观结构来提高个体功能。(1)采用溅射方法制备了Ag/MgO和/或W-N/AlN多层结构薄膜。随着银层厚度的增加，薄膜的光学性质由细小颗粒引起的表面等离激元吸收转变为体相金属性质的导电吸收，在近红外和可见光区域均有较大的吸收。在此基础上形成了功能梯度的Ag/MgO薄膜。太阳能总吸收率达到87%。在W-N/AlN系统上执行相同的过程。最终得到的功能梯度W-N/AlN薄膜的总太阳能吸收率为93%。(2)溅射Fe-Si薄膜在真空中(853K×2小时)进行热处理。测量了样品的电阻率(ρ)和塞贝克系数(α)的变化。由FeSiィイD22ィエD2组成的薄膜具有最大的ρ和α值。形成了FeSi-ィイ-D22-ィエ-D2/C多层膜。成功地降低了ρ的值，但也降低了α。功率因数并没有因此而提高。还形成了溅射的Co-Sb薄膜。经退火处理后，非晶态薄膜转变为纳米级高密度空穴的多晶结构。这种纳米空穴结构可能会导致导热系数的降低。本研究提出，在本征薄膜结构中引入合适的介观结构可以有效地改善固有功能。如何进行优化将是一个未来的问题。