ZnO nanotubes play a substantial role in various optoelectronic applications such as light-emitting diodes, solar cells and photodetectors. In this study, the structural, electronic, and optical effects of (n,0) single-walled ZnO nanotubes with different radius are discussed. An ab-initio approach of density functional theory with the generalized gradient approximation has been done by Quantum ESPRESSO software on nanotubes with n = 3 to 6. All simulated ZnO nanotubes illustrate semiconducting behavior, which due to the quantum confinement effect, the band gap value decreases by the increase in diameter. Moreover, optical characteristics including dielectric function $\mathrm{\epsilon }\left(\mathrm{\omega }\right)$, refractive index n($\mathrm{\omega })$, optical absorption coefficient $\mathrm{\alpha }\left(\mathrm{\omega }\right)$, conductivity $\mathrm{\sigma }\left(\mathrm{\omega }\right)$, energy loss spectrum L($\mathrm{\omega })$ and reflectivity R$\left(\mathrm{\omega }\right)$ have been analyzed and compared. The predicted optical features show that the mentioned nanotubes transmit light in perpendicular polarization better than parallel one and present superior reflect characters. Additionally, ZnO NTs act as a good absorbent in the visible wavelength which they can absorb various colors of the visible spectrum or even UV emission by altering the number of n. This ability turns ZnO NTs into remarkable photodetectors. Furthermore, according to optical characteristics like energy loss spectrum and dielectric function, it is obvious that results are approximately similar for different nanotubes and despite the miner red-shift of the position of the main peak, their appearance is close to each other. Therefore, ZnO NTs can be utilized in various applications such as optical filters, polarizers, and UV shields.

ZnO 纳米管在各种光电应用中发挥着重要作用，例如发光二极管、太阳能电池和光电探测器。在这项研究中，讨论了具有不同半径的 (n,0) 单壁 ZnO 纳米管的结构、电子和光学效应。Quantum ESPRESSO 软件在 n = 3 到 6 的纳米管上完成了密度泛函理论的从头算方法和广义梯度近似。所有模拟的 ZnO 纳米管都说明了半导体行为，由于量子限制效应，带隙值随着直径的增加而减少。此外，包括介电函数在内的光学特性$\mathrm{\epsilon }\left(\mathrm{\omega }\right)$, 折射率 n($\mathrm{\omega })$, 光吸收系数 $\mathrm{\alpha }\left(\mathrm{\omega }\right)$, 电导率 $\mathrm{\sigma }\left(\mathrm{\omega }\right)$, 能量损失谱 L($\mathrm{\omega })$ 和反射率 R$\left(\mathrm{\omega }\right)$进行了分析和比较。预测的光学特征表明，所提到的纳米管在垂直偏振中比平行偏振更好地传输光，并具有优异的反射特性。此外，ZnO NTs 在可见光波长中充当良好的吸收剂，它们可以通过改变 n 的数量来吸收可见光谱的各种颜色甚至紫外线辐射。这种能力将 ZnO NTs 变成了卓越的光电探测器。此外，根据能量损失谱和介电函数等光学特性，显然不同纳米管的结果大致相似，尽管主峰位置有矿工红移，但它们的外观彼此接近。因此，ZnO NTs 可用于各种应用，例如滤光片、偏光片和紫外线防护罩。