Abstract Despite the recent increase in PPDT2FBT polymer thin film applications for optoelectronic devices, a comprehensive study of this material's optical dispersion properties is unavailable. The optical properties of the PPDT2FBT thin film is investigated using variable-angle spectroscopic ellipsometry (VASE) at ambient conditions. Knowledge of optical dispersion properties is essential for designing and fabricating optoelectronic devices such as solar cells, photodetectors, and photodiodes. In this research, we determined the dielectric function of PPDT2FBT thin film using the B-spline model and then reproduced the dielectric function using Psemi-Tri oscillators. We estimated the refractive index (n) of the thin film to be between 2.00 and 2.15 and the extinction coefficient (k) to be in the range of 1.14–1.39 at a wavelength of 632.8 nm. We further verified the estimated optical properties from the model using directly measured quantities such as transmission and absorption data obtained using the ultraviolet–visible (UV–Vis) spectrometer and thicknesses obtained using a surface profilometer. In addition, we determined the optical band gap of PPDT2FBT using the absorption coefficient.

中文翻译：

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使用光谱椭偏法测定 PPDT2FBT 薄膜的折射率和介电常数

摘要 尽管最近 PPDT2FBT 聚合物薄膜在光电器件中的应用有所增加，但仍无法对该材料的光学色散特性进行全面研究。在环境条件下使用可变角度光谱椭偏仪 (VASE) 研究了 PPDT2FBT 薄膜的光学特性。光色散特性的知识对于设计和制造光电器件（如太阳能电池、光电探测器和光电二极管）至关重要。在这项研究中，我们使用 B 样条模型确定了 PPDT2FBT 薄膜的介电函数，然后使用 Psemi-Tri 振荡器重现了介电函数。我们估计薄膜的折射率 (n) 在 2.00 和 2.15 之间，消光系数 (k) 在 632.8 nm 的波长范围内在 1.14-1.39 之间。我们使用直接测量的量（例如使用紫外-可见（UV-Vis）光谱仪获得的透射和吸收数据以及使用表面轮廓仪获得的厚度）进一步验证了模型中估计的光学特性。此外，我们使用吸收系数确定了 PPDT2FBT 的光学带隙。