Synthesis, Optical and Photovoltaic Properties of Porphyrin Dyes

Abstract

The synthesis and optical absorption of a series of porphyrins, and the photoelectrochemical properties of TiO 2 solar cells sensititized with these porphyrins was investigated. The different types of porphyrins studied are designated by numbers: the reference compound 1 (Zinc(II) 5,15-bis(4-carboxylphenyl)porphyrin), porphyrin substituted with one triarylamine unit 2, and porphyrin substituted with two triarylamine units 3. The UV-Vis absorption spectra reveal that the substitutions result in large redshifts in both the Soret band (∼60 nm) and the Q bands (∼125 nm), as well as enhancement of optical absorption. The enhancement is even more pronounced in the long-wavelength region of 575-725 nm, where the absorption of porphyrin 3 is eight times that of porphyrin 1. The photoelectrochemical properties of the porphyrins were also studied by constructing porphyrin-sensitized TiO 2 solar cells. Under standard AM 1.5 sunlight, the porphyrin 1 cell yields a short-circuit current of ∼1.26 mA/cm2 , an open-circuit voltage of ∼0.564 V, and a fill factor of ∼61%. The incident photon-to-current conversion efficiency is ∼24% for porphyrin 1 and ∼5-7% for porphyrins 2 and 3 at the Soret peak.

Large Cumulative Capacity Enabled by Regulating Lithium Plating with Metal–Organic Framework Layers on Porous Carbon Nanotube Scaffolds

“…After the chemical treatment of pristine CNT (P‐CNT), the vibration of CO in carboxylic acid appeared at 1729 cm −1 . [ 38,39 ] After MOF incorporation into CNT, the asymmetric and symmetric vibration of carboxylate (COO − ) at 1610 and 1434 cm −1 in C‐CNT were shifted to 1548 and 1413 cm −1 and the carboxylic acid peak was suppressed, suggesting a formation of a coordinate bonding between the carboxylate group and the Zr cluster in MOF. [ 38,39 ] According to the scanning electron microscope (SEM, JEOL JSM‐7500F) images, the surface and diameter of C‐CNT (Figure 1e) were noticeably altered after the MOF deposition, showing textured surfaces and bigger diameters for all the CNTs in IM‐CNT (Figure 1f).…”

Synthesis, spectroscopic characterization and singlet oxygen generation of 5,10,15,20-tetrakis(3,5-dimethoxyphenyl) porphyrin as a potential photosensitizer for photodynamic therapy

“…Accordingly, the presence of electron-rich OMe groups at the meso position of TdMPP gave rise to an increase in the aryl-porphyrin π -π resonance interactions. This had been attributed to the smaller dihedral angle between the aryl groups and the porphyrin mean plane in the excited state of porphyrins (S1) with respect to that in the ground state (S0) (Lee et al, 2009;Zakavi and Hoseini, 2015). Furthermore, the stokes shift of the porphyrin which describes the energy gap between the emission Q*x(0,0) and absorption Qx(0,0) bands is 4 nm which was an additional indication of minor structural changes of the porphyrin macrocycle in the ground and excited states (Ha et al, 2001).…”

Photoconductivity and photovoltaic properties of polyaniline immobilized onto metallurgical porous silicon powder

“…In recent years, the low cost, availability in bulk and ease of processing of flexible thin films has advanced molecular and macromolecular π‐conjugated organic compounds as a prime choice for PV applications in dye‐sensitized (Grätzel) and solid state solar cells . However, π‐conjugated organic materials are recognized to have two main drawbacks, namely a low power conversion efficiency of less than 5% due to rapid exciton decay and photo‐bleaching of the photoactive components that limits their lifetime .…”

“…), metal silicides (FeSi 2 ) and π‐conjugated molecular/macromolecular organic compounds (pentacene, polythiophenes, polyaniline etc. ) as feasible alternatives to semiconducting wafers. The common feature allowing these materials to be good candidates for PV applications is their ability to absorb light photons, leading to the formation of excitons (tightly bound electron–hole pairs) which can rapidly diffuse to the p–n junction (known as the donor–acceptor (D‐A) interface in organic systems), where they split into charge carriers (e – and h + ).…”

“…In contrast to layer‐by‐layer stacking/bulk blending processes where the contact distance between the D and A is limited by the components' particle sizes, physical/chemical immobilization of π‐conjugated organic materials onto inorganic semiconductors and colloidal self‐assemblies of π‐conjugated polymers in polymeric matrix systems are advantageous as they limit the contact distance to the molecular level. In this context, the role of the D‐A interface in enhancing photoconversion efficiency has been realized by different research groups …”