BODIPY substituted zinc(II) phthalocyanine and its bulk heterojunction application in solar cells

A novel asymmetrical zinc(II) phthalocyanine-BODIPY conjugate (ZnPc-BODIPY) bearing three iodine groups directly substituted to the macrocycle and one BODIPY connected to the macrocycle with an amide bond was synthesized by the reaction of carboxylic-acid-substituted asymmetrical zinc(II) phthalocyanine (ZnPc) with the BODIPY-derivative-bearing amino group (BODIPY-NH2). This conjugate was fully characterized by spectroscopic methods (FT-IR, UV-vis, 1H NMR, 11B NMR, 19F NMR and mass) and elemental analysis. The fluorescence behavior of ZnPc-BODIPY was studied to determine the energy transfer process. Voltammetry measurements (CV and SWV) were performed to specify the HOMO–LUMO energy levels and band gaps of ZnPc-BODIPY and starting compounds (ZnPc and BODIPY-NH2) for comparison. In addition, the band gaps of these compounds were also determined by UV-vis absorption onset (λonset) and theoretical calculations. Bulk heterojunction solar cells containing ZnPc-BODIPY were fabricated in the structure of ITO/PEDOT:PSS/ZnPc-BODIPY:PCBM/Al. The photovoltaic parameters of the solar cell were obtained and the ZnPc-BODIPY conjugate was found to bring spectral contribution to IPCE at a peak of 510 nm.

Synthesis, Spectral, Electrochemical and Photovoltaic Studies of A3 B Porphyrinic Dyes having Peripheral Donors

Three new 'push-pull' A₃ B Zn(II)porphyrin dyes having meso-pyrenyl, carbazolyl and phenothiazine as electron donors (A) and phenylcarboxylic acid as acceptor/anchor (B) were synthesized and utilized for DSSC application. The spectral and electrochemical redox properties of these new dyes were studied and compared with trans-A₂ BC Zn(II) porphyrin dyes under similar experimental conditions. Red-shifted, broadened absorption peaks, lower fluorescence quantum yields, and shortened lifetimes were observed for the A₃ B dyes as compared to zinc tetraphenylporphyrin control, ZnTPP. DFT optimized structures suggested effective charge separation related to enhanced charge injection efficiency. Driving force for electron injection (ΔG_inj ) and dye regeneration (ΔG_reg ) calculated from the spectral and electrochemical studies predicted facile electron injection from excited dye into semiconductor TiO₂ in the constructed solar cells. Phenothiazine appended dye (KP-TriPTZ-Zn) showed the highest η value of 7.3 % for PCE with greater J_sc and V_oc values due to its better light harvesting ability and reduced dye aggregation as compared to other dyes. Our studies demonstrate that the dyes having multiple electron-donating groups exhibit higher photon-to-current conversion efficiency.

Complexes between core-modified porphyrins ZnP(X)4 (X = P and S) and small semiconductor nanoparticle Zn6S6: are they possible?

The synthetic approach of the anchoring of porphyrins to the surface of semiconductor nanoparticles (NPs) has been realized to form very promising organic/inorganic nanocomposites. They have been of considerable scientific and a wide practical interest including such areas as material science, biomedical applications, and dye-sensitized solar cells (DSSCs). Macrocyclic pyrrole-containing compounds, such as phthalocyanines and porphyrins, can bind to the NP surface by a variety of modes: as monodentate ligands oriented perpendicular to the NP surface, parallel to the NP surface, or, alternatively, in a perpendicular orientation bridging two adjacent NPs. Also, non-covalent (coordination) interactions may be realized between the NP via its metal centers and appropriate meso-attached groups of porphyrins. Recently, we showed computationally that the prominent structural feature of the core-modified MP(X)4 porphyrins (X = P) is their significant distortion from planarity. Motivated by the phenomenon of numerous complexes formation between tetrapyrrols and NPs, we performed the density functional theory (DFT) studies of the complex formation between the core-modified ZnP(X)4 species (X = P and S) without any substituents or linkers and semiconductor NPs, exemplified by small NP Zn6S6. The complexes formation was investigated using the following theoretical approaches: (i) B3LYP/6-31G* and (ii) CAM-B3LYP/6-31G*, both in the gas phase and with implicit effects from C6H6 considered. The calculated binding energies of the complexes studied were found to be significant, varying from ca. 29 up to ca. 69 kcal/mol, depending on the complex and the approach employed.

Reactive Porphyrin Adsorption on TiO2 Anatase Particles: Solvent Assistance and the Effect of Water Addition

The surface functionalization of metal oxide nanoparticles with complex organic molecules can lead to optoelectronically very different material properties, depending on whether adsorption occurs at the solid-gas or solid-liquid interface. Here, we report on two different approaches to decorate anatase TiO₂ nanoparticle powders with 2 H-tetraphenylporphyrin (2HTPP) molecules: (i) porphyrin adsorption in dispersions of organic liquids and (ii) gas-phase functionalization where evaporated porphyrin molecules attach to dehydrated particle surfaces in the absence of solvent molecules. In the latter case, a bottom-up approach is pursued to explore both the impact of organic solvent molecules and the impact of spurious water on the surface chemistry of porphyrin-sensitized TiO₂ nanoparticles. Vis diffuse reflectance and photoluminescence emission spectroscopy provide clear evidence for the promotion of interfacial reorganization processes of the adsorbate species by coadsorbed solvent molecules in liquids. Moreover, traces of spurious water were found to induce protonation-deprotonation reactions on the adsorbed porphyrins with a strong impact on the optical properties of the resulting hybrid materials.

Polymer matrices for porphyrin nanorods incorporation. Artificial light harvesting applications

This contribution is focused on the supramolecular approach in exploration of aggregates formation by two different porphyrins wherein self-assembly plays an important role. Spectroscopic and microscopic studies usually provide information on investigations regarding the effects of various parameters on the fabrication of porphyrin aggregates by ionic self- assembly. Various properties of ionic self-assembled porphyrin nanorods have been investigated, including nonlinear optical (NLO) properties, and these studies were influenced by the fact that porphyrins have great thermal stability and extended [Formula: see text]conjugated macro cyclic rings which give them large nonlinear optical effects. The major reasons limiting porphyrin nanorods photonic applications include the difficulty of handling them in liquid solutions and their degradation with long exposure to light. This necessitates the use of appropriate solid matrices to host the nanorods. Inspired by the precise organization and orientation of the chromophores in natural systems, attention has been on the design of nanometer sized chromophoric assemblies, which may find applications in the field of molecular photonics. However, it is challenging to design multicomponent systems with controlled structural arrangement at the molecular level. A lack of precise arrangement may have a negative impact on the construction of an efficient artificial light harvesting system. This review is focused on exploring the possibility of incorporating nanorods into polymer matrices to overcome the limiting factors of applications of these materials in photonic devices.

Fabrication of carbon nanotube-multiporphyrin array composites as light-sensitizer for photocurrent generation, photochromism of viologen and catalytic degradation of methyl orange

Multiporphyrin arrays were assembled on the surface of MWNTs to produce light-sensitive nano-composites with improved opto-electric conversion efficiency, photochromic, and photocatalytic performance.

Solid state structures and properties of free-base 5,10,15-triphenylcorrole (TPCor) anions obtained by deprotonation and reduction. Effective magnetic coupling of spins in (Cp*2Cr+)(H+)(H2TPCor˙2−)·C6H4Cl2

The structures and properties of free-base triphenylcorrole radical H2TPCor˙²⁻ dianions and diamagnetic deprotonated H2TPCor⁻ anions have been studied. In both cases, deprotonation provides a planar shape of the corrole macrocycle. High-spin Cp*₂Cr⁺ (S = 3/2) and H2TPCor˙²⁻ with the S = 1/2 spin state alternate in the π-stacks providing effective antiferromagnetic coupling of spins.

Synthesis, crystallographic characterization and homogeneous catalytic activity of novel unsymmetric porphyrins

Unsymmetric porphyrins containing both pentafluorophenyl (PFP = A) and 3,4-dimethoxyphenyl (DMP = B) substituents at the meso positions were prepared using Lindsey's methodology.

Azaporphyrin phosphorus(v) complexes: synthesis, structure, and modification of optical properties

Azaporphyrinoids, such as phthalocyanines (Pcs), tetraazaporphyrins (TAPs), and tetrabenzotriazacorroles (TBCs), are some of the most well-known and successful artificial dyes and pigments in modern material chemistry.

Preparation, X-ray Structures, Spectroscopic, and Redox Properties of Di- and Trinuclear Iron-Zirconium and Iron-Hafnium Porphyrinoclathrochelates

The first hybrid di- and trinuclear iron(II)-zirconium(IV) and iron(II)-hafnium(IV) macrobicyclic complexes with one or two apical 5,10,15,20-tetraphenylporphyrin fragments were obtained using transmetalation reaction between n-butylboron-triethylantimony-capped or bis(triethylantimony)-capped iron(II) clathrochelate precursors and dichlorozirconium(IV)- or dichlorohafnium(IV)-5,10,15,20-tetraphenylporphyrins under mild conditions. New di- and trinuclear porphyrinoclathrochelates of general formula FeNx₃((Bn-Bu)(MTPP)) and FeNx₃(MTPP)₂ [M = Zr, Hf; TPP = 5,10,15,20-tetraporphyrinato(2-); Nx = nioximo(2-)] were characterized by one-dimensional (¹H and ¹³C{¹H}) and two-dimensional (COSY and HSQC) NMR, high-resolution electrospray ionization mass spectrometry, UV-visible, and magnetic circular dichroism spectra, single-crystal X-ray diffraction experiments, as well as elemental analyses. Redox properties of all complexes were probed using electrochemical and spectroelectrochemical approaches. Electrochemical and spectroelectrochemical data suggestive of a very weak, if any, long-range electronic coupling between two porphyrin π-systems in FeNx₃(MTPP)₂ complexes. Density functional theory and time-dependent density functional theory calculations were used to correlate spectroscopic signatures and redox properties of new compounds with their electronic structures.