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.

为了开发利用太阳能资源，研究了光-热-电能量转换功能薄膜。该主题由两个功能部分组成，即，(1)光热能转换膜和（2）热电能转换膜。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)用溅射法制备了Ag/MgO和/或W-N/AlN多层结构薄膜。随着Ag层厚度的增加，光学性质从由于细颗粒引起的表面等离子体吸收转变为通过导电吸收的体金属性质，其在近红外区域以及可见光区域显示出相对大的吸收。基于上述结果形成了功能梯度Ag/MgO膜。然后实现87%的总太阳能吸收率。在W-N/AlN系统上执行相同的程序。最终获得的功能梯度W-N/AlN薄膜显示出93%的总太阳能吸收率。(2)溅射的Fe-Si薄膜在真空中退火（853 K × 2 h）。测量了电阻率（ρ）和塞贝克系数（α）的变化。当薄膜的组成为FeSi_xD_22_xD_2时，薄膜的ρ和α值最大。形成了多层FeSi_xD_22_xD_2/C薄膜。ρ的值成功地降低了，但α也降低了。因此功率因数没有得到改善。溅射Co-Sb薄膜也形成。通过退火，非晶结构的薄膜转变为多晶结构，包括纳米尺寸的高密度空洞。这种纳米空隙结构可能有助于降低热导率。本研究表明，在本征膜结构中引入合适的介观结构可以有效地改善固有功能。优化的执行将是未来的问题。