Light-harvesting efficiency of a (6,5) carbon nanotube functionalized with a free-base tetraphenylporphyrin: Density functional theory calculations

Using ab initio calculations, we study the optical absorption of a free-base tetraphenylporphyrin (TPP) noncovalently attached onto a (6,5) semiconducting carbon nanotube (CNT). The optical properties of the CNT-TPP assembly were obtained through the imaginary part of the dielectric function in the linear optical response, whereas the light-harvesting efficiency is estimated through adsorbed and delivered irradiance calculations on a CNT-TPP thin film. Our results suggest that the maximum efficiency could reach 40 for a 100 nm thick film, stabilizing in this value for thicker films. We also found a strong dipole-dipole interaction at the CNT-TPP interface not observed on achiral CNTs, suggesting that the high efficiency in the excitation energy transfer measured in this assembly would be originated in a resonance transfer process induced by the CNT chirality.