Numerical calculation of visible light absorption enhancement of CdSe-quantum dot-sensitized TiO₂ nanorod periodic array as photoanode

Abstract

Light absorption enhancement in a CdSe-quantum dot (QD)-sensitized TiO2 nanorod periodic array-based photoanode is calculated by the finite differential time domain (FDTD) model through optimizing the height, diameter, and periodic space between TiO2 nanorods. Results show that light absorption in the CdSe-QD-sensitized TiO2 nanorods is enhanced at the visible wavelength range and the absorption edge is shifted toward higher wavelengths as a result of decreasing the height and increasing the diameter of the TiO2 nanorods. Consequently, the equivalent bandgap of the CdSe-QD-sensitized TiO2 nanorod photoanode was decreased. Also, absorption spectra indicate that the position of the absorption peak related to TiO2 has a redshift with increasing periodic space between the TiO2 nanorods, suggesting a decrease in the bandgap of TiO2. In addition, results show that for TiO2 nanorod heights lower than 300 nm, light absorption in the visible region is considerably enhanced as the periodic space is reduced from 400 nm to 100 nm. In comparison, for TiO2 nanorod heights larger than 300 nm, light absorption is considerably enhanced. Finally, it is found from absorption spectra that coupling optical modes of TiO2 nanorods and CdSe QDs are enhanced by increasing the diameter and decreasing the height and periodic space between the TiO2 nanorods. As a result, the light absorption is increased in the photoanodes at the visible region, leading to an improvement in the performance of the photoanode at visible light.

Quantum Dot-sensitized Solar Cells: A Review

“…There are two basic reasons because of that, properties of nanostructures change with their shape and size: quantum confinement effect and increment of volume to surface area ratio [21]. Various QD's such as CdS [22], CdSe [23], PbS [24], PbSe [25] have been used as sensitizer in QDSSCs. QDs have special features like Multiple exciton generation (MEG) of carrier [26], tunable optical band gap and broad optical absorption regions of solar spectrum [27], Hot electron injection [28].…”

Light Absorption Enhancement and Laser-Induced Damage Ability Improvement of Aluminum Alloy 6061 with Non-Porous Alumina/CdSe@Al2O3/SiO2 Functional Gradient Films

“…This requires light-absorbing materials in the pores of anodic aluminum oxide (AAO), which is a commonly used chemical conversion film formed on the surface of aluminum alloy. CdSe quantum dots (QDs) have been used to absorb light with relatively low cost [ 16 , 17 ]. Recently, Kohnehpoushi et al [ 17 ] described visible light absorption enhancement in a CdSe-QD-sensitized TiO 2 periodic nanorod array.…”

“…CdSe quantum dots (QDs) have been used to absorb light with relatively low cost [ 16 , 17 ]. Recently, Kohnehpoushi et al [ 17 ] described visible light absorption enhancement in a CdSe-QD-sensitized TiO 2 periodic nanorod array. The enhancement mechanism was related to the diameter, height, and periodic spacing of the TiO 2 nanorods.…”