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Dye-sensitized photocatalytic systems (DSPs) have emerged as a promising strategy to achieve efficient and stable solar-driven H2 evolution systems. In this work, we prepared and tested a series of zinc-trimesityl porphyrin carboxylic acid derivatives as photosensitizes in DSPs for H2 evolution. In order to unveil the influence of the anchoring group, different positions of the carboxylic acid were studied. All porphyrins were adsorbed onto platinum-doped titanium dioxide nanoparticles (Pt-TiO2 NPs) and were irradiated by a white LED source. The DSPs coated with Zn-TM(pCOOH)P(i.e. the carboxylic acid at the para-phenyl position) illustrated increased stability (2514 TONs for 1.0 × 10[Formula: see text] M) and the highest H2 evolution activity (1959 mmol g[Formula: see text] h[Formula: see text] for 1.5 × 10[Formula: see text] M). These results reveal that efficient and stable DSPs for H2 evolution can be developed by utilizing porphyrin derivatives as photosensitizers.

A stable system containing a Pt metalated porphyrin as a molecular solid photocatalyst in acidic aqueous solution is able to produce hydrogen efficiently, under visible light irradiation.

The presence of defects formed during the growth and crystallization of perovskite films is a limiting factor to achieve high efficiency and stability in perovskite solar cells.

This review summarizes the recent advances in light driven catalytic H2 evolution and CO2 reduction systems towards the production of solar fuels, utilizing porphyrin or phthalocyanine derivatives.

We synthesized a simple zinc(ii) tetraphenyl porphyrin, ZnTPP and studied the three different self-assembled architectures obtained with the use of a “bad”/“good” solvent protocol.

International audience; The photocatalytic CO 2 reduction into value-added chemicals is regarded as one promising technology to mitigate environmental issues and the energy crisis of the modern world due to the extended CO 2 emissions. Recent advances have shown that iron porphyrins are considered as one of the most efficient molecular catalysts in the activation and reduction of molecules like CO 2. Thus, we have prepared a suitably modified Fe III porphyrin ([Fe III (TF 4 TMAP)](CF 3 SO 3) 5) and studied its catalytic activity in terms of photocatalytic reduction of CO 2. This iron catalyst possesses four fluorine substituents in the ortho and the meta position of each meso-phenyl group of the porphyrin, while trimethyl-ammonium groups were placed in the para position. Photocatalytic studies were performed in the presence of an iridium complex as a chromophore and have shown that [Fe III (TF 4 TMAP)](CF 3 SO 3) 5 can effectively reduce CO 2, achieving excellent turnover numbers (up to 5500 TONs) and high turnover frequencies. The main reduction product of this photocatalytic system was CO, and only a small amount of hydrogen was detected, presenting a maximum selectivity of 86% for CO.

International audience; In this study, we report the preparation of BODIPY-(Zn)Porphyrin hybrids and their utilization in photocatalytic H 2 production from water. These entities were employed as photosensitizers upon their chemisorption onto the surface of platinum-doped titanium dioxide nanoparticles (PtTiO 2) which acted as photocatalysts. We prepared two diverse BODIPY-(Zn)Porphyrin entities, in which the BODIPY moiety is either covalently attached (BDP-Por) or axially coordinated (BDP(Im)-Por) with the (Zn)Porphyrin; in order to evaluate the impact of the different connectivity between the chromophores in photocatalytic in H 2 evolution. Overall, we developed highly efficient dye-sensitized photocatalytic systems (DSPs) based on noble metal-free photosensitizers reaching 18,600 Turnover Numbers (TONs) and 225 mmol(H 2) g(cat)-1 h-1 .

The investigation of molecular model systems is fundamental towards a deeper understanding of key photochemical steps in natural photosynthesis. Herein, we report an entirely non-covalent triad consisting of boron dipyrromethene (BDP), porphyrin (ZnP), and fullerene (C60). Non-covalent binding motifs such as an amidinium-carboxylate salt bridge as well as axial pyridyl-metal coordination offer substantial electronic coupling and establish efficient pathways for photoactivated energy and electron transfer processes along a well-tuned gradient. Experimental findings from steady-state and time-resolved spectroscopic assays, as well as (spectro-)electrochemical measurements corroborate the formation of BDP|ZnP|C60 in solution, on one hand, and significant communication in the excited states, on the other hand. BDP acts as an energy harvesting antenna towards ZnP, which eventually undergoes charge separation with C60 by electron transfer from ZnP to C60. Notably, full spectral deconvolution of the transient species was achieved, supporting the successful self-assembly as well as giving a clear view onto the occurring photophysical processes and their spectral footprints upon photoexcitation.

High-performance perovskite light-emitting diodes (PeLEDs) require a high quality perovskite emitter and appropriate charge transport layers to facilitate charge injection and transport within the device. Solution-processed n-type metal oxides represent a judicious choice for the electron transport layer (ETL); however, they do not always present surface properties and energetics compatible with the perovskite emitter. Moreover, the emitter itself exhibits poor nanomorphology and defect traps that compromise the device performance. Here, we modulate the surface properties and interface energetics between the tin oxide (SnO2) ETL with the perovskite emitter by using an amino functionalized difluoro{2-[1-(3,5-dimethyl-2H-pyrrol-2-ylidene-N)ethyl]-3,5-dimethyl-1H-pyrrolato-N}boron compound and passivate the defects present in the perovskite matrix with carbon-polymer core–shell quantum dots inserted into the perovskite precursor. Both these approaches synergistically improve the perovskite layer nanomorphology and enhance the radiative recombination. These properties resulted in the fabrication of near-infrared PeLEDs based on formamidinium lead iodide (FAPbI3) with a high radiance of 92 W sr−1 m−2, an external quantum efficiency (EQE) of 14%, reduced efficiency roll-off and prolonged lifetime. In particular, the modified device retained 80% of the initial EQE (T80) for 33 h compared to 6 h of the reference cell.

Herein, we illustrate the preparation of a covalent connected peptide–porphyrin hybrid (Fmoc-FF-(Zn)Por). The thorough investigation of its self-organization features demonstrated that Fmoc-FF-(Zn)Por self-assembles into either spheres or fibrils by altering the solvent mixture. Interestingly, photocatalytic hydrogen (H2) evolution experiments revealed that fibrils were more efficient towards H2 production compared to spheres.

Carbon dots and nitrogen doped carbon dots were effectively synthesized and characterized. Their use as light harvesters was examined in the presence of three different cobalt-based catalysts and tris(carboxyethyl)phosphine/ascorbic acid (TCEP/Asc), as the sacrificial electron donor (SED). The electrons are transferred from the valence band (VB) to the conduction band (CB) of the carbon dots and the holes that are formed are filled by electrons transferred from the SED. The best photocatalytic system reported herein produces 17.1 μmol of H2 (TONCAT = 859) under UV radiation for 52 h. The same system can produce 5.3 μmol of H2 (TONCAT = 264) under the Cretan sun for 21 days of solar irradiation.

An interfacial engineering approach was adopted in order to optimize the photovoltaic parameters and the stability of n-i-p planar perovskite solar cells (PSCs). A thin manganese (Mn) porphyrin [(T...

In this study, a series of diphenylalanine tetra-substituted porphyrin derivatives were synthesized and their self-assembly ability was extensively studied. Apart from investigating the impact of incorporating many peptide moieties onto a porphyrin molecule; another perspective was investigated as well, namely the connection of two different chromophore entities (porphyrin and BODIPY) onto the same diphenylalanine molecule. Interestingly, various supra-molecular nanostructures were observed depending on the solvent mixture as well as the protecting group of the peptides, namely spheres, plaques and fibrils. The obtained self-assemblies were studied via UV-vis absorption and emission spectroscopies. Mainly red shifting was observed, indicating the formation of [Formula: see text]-aggregates in the self-assembled state. However, in one case a blue shifted UV-vis spectrum was obtained suggesting the formation of [Formula: see text]-type aggregates. Concerning the porphyrin-diphenylalanine-BODIPY derivative, additional fluorescence studies were performed in order to examine a possible interaction between the two chromophores in the excited state. Indeed, the emission measurements indicated that upon photo-excitation of the BODIPY entity, a very efficient energy or electron transfer process takes place from the BODIPY molecule to the porphyrin macrocycle.

Cytotoxic potential of Ag(i) coordination compounds against cancer cells is widely recognized, but their frequently low water solubility and potential adverse interactions of Ag(i) ions in biological media require their incorporation into suitable platforms to ensure effective transport and delivery at target sites. Herein, we developed and evaluated the in vitro cytotoxic activity of a biodegradable copolymer-based nano-sized drug delivery system for three cytotoxically active and lipophillic Ag(i) compounds. In particular, polymer-based nanoparticles of the newly synthesized amphiphilic methoxy-poly(ethylene glycol)–poly(caprolactone) (mPEG–PCL) copolymer were prepared as carriers for [Ag(dmp2SH)(PPh(3))(2)]NO(3) (1), [Ag(dmp2SH)(xantphos)]NO(3) (2) and [Ag(dmp2S)(xantphos)] (3) (dmP2SH = 4,6-dimethylpyrimidine-2-thiol, xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) which exhibit high cytotoxicity against HeLa cancer cells, while they maintain low toxicity against HDFa normal cells. Taking advantage of the favorable donor–acceptor Lewis acid–base and electrostatic interactions between functional groups of 1–3 and mPEG–PCL copolymer, the formation of [X]@mPEG–PCL (X = 1,2,3) nanoparticles with nearly spherical shape was achieved. Satisfactory loading capacities and encapsulation efficiencies were obtained (13–15% and 80–88%, respectively). Differences in their mean size diameters were observed, revealing a dependence on the individual structural characteristics of the Ag(i) compounds. In vitro release profiles of the nanoparticles showed an initial burst stage, followed by a prolonged release stage extending over 15 days, with their release rates being determined by the mean size of the nanoparticles, as well as the type and crystallinity of the encapsulated Ag(i) compounds. In vitro cytotoxicity studies revealed an increased cytotoxic activity of compounds 1–3 after their encapsulation in mPEG–PCL copolymer against HeLa cells, with the actual concentrations of the loaded compounds responsible for the inhibition of cell viability being reduced by 8 times compared to the compounds in free form. Therefore, the current drug delivery system improves the pharmacokinetic properties of the three cytotoxic and biocompatible Ag(i) compounds, and may be beneficial for future in vivo anticancer treatment.

We report a comparison between a series of zinc and tin porphyrins as photosensitizers for photochemical hydrogen evolution using cobaloxime complexes as molecular catalysts. Among all the chromophores tested, only the positively charged zinc porphyrin, [ZnTMePyP4+]Cl4, and the neutral tin porphyrin derivatives, Sn(OH)2TPyP, Sn(Cl2)TPP-[COOMe]4, and Sn(Cl2)TPP-[PO(OEt)2]4, were photocatalytically active. Hydrogen evolution was strongly affected by the pH value as well as the different concentrations of both the sensitizer and the catalyst. A comprehensive photophysical and electrochemical investigation was conducted in order to examine the mechanism of photocatalysis. The results derived from this study establish fundamental criteria with respect to the design and synthesis of porphyrin derivatives for their application as photosensitizers in photoinduced hydrogen evolution.

Semiconductor colloidal quantum dots (CQDs) offer size- and composition-tunable luminescence of high colour purity. Importantly, their emission can be tuned deep into the second biological near-infrared (NIR-II) window (1,000–1,700 nm). However, applications are hindered by the low efficiencies achieved to date. Here, we report NIR-II CQD light-emitting diodes with an external quantum efficiency of 16.98% and a power conversion efficiency of 11.28% at wavelength 1,397 nm. This performance arises from device engineering that delivers a high photoluminescence quantum yield and charge balance close to unity. More specifically, we employed a binary emissive layer consisting of silica-encapsulated silver sulfide (Ag2S@SiO2) CQDs dispersed in a caesium-containing triple cation perovskite matrix that serves as an additional passivation medium and a carrier supplier to the emitting CQDs. The hole-injection contact also features a thin porphyrin interlayer to balance the device current and enhance carrier radiative recombination. Semiconductor nanocrystals with efficient tunable emission in the 1,000–1,700 nm window could prove useful for applications in deep biological imaging and sensing.

Two hybrid materials were designed by conjugating peptide nucleic acids (PNAs) to porphyrin or boron-dipyrromethene, generating PNA-porphyrin (PNA-TPP) and PNA-BODIPY (PNA-BDP) conjugates, respectively. Because of the combination of the supramolecular characteristics of PNAs and photosensitizers, the two hybrid conjugates readily self-assemble in aqueous solutions and produce well-defined nanoparticles with uniform particle sizes. The resulting two kinds of nanoparticles show good stability in biological solutions and upon dilution. Importantly, the nanoparticles can efficiently interact with cancer cells and the internalized nanoparticles are mainly distributed in the cytoplasm without discernible cytotoxicity in the dark, enabling them to be applied as photodynamic nanoagents for selective killing cells. Hence, self-assembly of PNA-photosensitizer conjugates may hold promise for advancing the rational design and construction of photodynamic nanoagents for cancer therapy.

The syntheses of indium, gallium and aluminum porphyrin dimers with a single hydroxo-bridge, [Formula: see text][M(Porph)]2(OH)[Formula: see text], are described. Emphasis is given to indium and gallium derivatives. The X-ray structures for [Formula: see text] [Ga(OEP)]2(OH)[Formula: see text] ClO4 and [Formula: see text] [In(OEP)]2(OH)[Formula: see text] ClO4 (two forms) are presented. The dimeric molecules can be synthesized by the acid-treatment of the corresponding hydroxo-ligated monomeric complexes [M(OEP)(OH)] and [M(TPP)(OH)]. The nature of the starting material (the hydroxo-ligated monomer) was first suggested by IR spectroscopy and further proved by proton-deuterium exchange followed by 1H NMR spectroscopy. The structure of a monomeric indium hydroxide complex, [In(OEP)(OH)], is also presented. The synthesis of the dimer for all metals can be monitored by UV-vis spectroscopy, which clearly demonstrates that a blue-shift of the Soret band accompanies formation of the dimer from the monomer. A strong [Formula: see text]–[Formula: see text]interaction between the two porphyrin rings of these [Formula: see text]-hydroxo-bridged dimers is confirmed both by solution state studies (1H NMR and UV-vis spectroscopy) and the X-ray structures of [Formula: see text] [M(OEP)]2(OH)[Formula: see text] ClO4 (M = In, Ga). In addition, exposure of methylene chloride solutions of these bridged complexes to white light afforded the corresponding chloro derivatives, [M(Porph)Cl]. The stereochemistry of a range of [Formula: see text]-hydroxo dimers is discussed and DFT simulations at the HSEH1PBE/SDD level of theory provide suitable structural models and further electronic structure insights on selected [Ga(Porph)(OH)] and [Formula: see text] [Ga(Porph)]2(OH)[Formula: see text][Formula: see text] derivatives.

In this study, two porphyrin chromophores metallated with ruthenium, RuTBP and RuTBPPy, were prepared and studied as sensitizers in dye-sensitized solar cells (DSSCs). The difference between the two dyes is the position (axial vs. peripheral) of the carboxylic anchoring group. This work examines the impact of this variation towards the optical, electrochemical and photovoltaic performance of DSSCs. The thorough photophysical and photovoltaic measurements indicated that the peripherally substituted sensitizer (RuTBP) presented higher photovoltaic performance compared to RuTBPPy. More specifically, DSSCs sensitized with RuTBP and RuTBPPy displayed an overall power conversion efficiency (PCE) of 5.12% and 4.08%, respectively. The higher PCE value of the DSSC sensitized with RuTBP is mainly attributed to the enhancement of [Formula: see text] and FF values. These factors were enhanced due to the efficient dye regeneration process, the suppression of back-charge recombination reactions and the longer electron lifetimes as evidenced from the electrochemical impedance spectra.

The synthesis, characterization, and application in light‐emitting electrochemical cells (LECs) of two near‐infrared (NIR)‐emitting Pt‐porphyrins (Pt‐por) with none or 20 F atoms and their respective Pt‐por polyads containing from 1 to 4 BODIPY (BDP) units (PtBDP) connected via tetra‐fluorophenyl triazole spacer groups are reported. The functionalization of PtBDPs is tuned with respect to the number of BDP units and F atoms optimizing 1) the NIR emission through an efficient energy transfer from the BDP to the Pt‐por core, 2) the electronic structure to decouple charge transport via BDP and exciton formation at the Pt‐por, and 3) the ionic conductivity in thin films. A comprehensive rationale on how the molecular design rules the device performance is provided, achieving LECs with emission at 780 nm. This is realized using PtBDP‐2‐8, in which a host:guest strategy between BDP and Pt‐por in thin films is fully operative accompanied by an optimal ionic conductivity. This is supported by spectroelectrochemical findings and device analysis with both Pt‐por references and the PtBDP series. Overall, this work highlights that Pt‐porphyrins are efficient emitters in developing NIR LECs due to their rich functionalization, enabling to control charge transport, energy transfer, and ionic conductivities.

International audience; The utilization of solar energy via photoelectrochemical cells (PEC) towards hydrogen (H2) production is a promising approach in the field of artificial photosynthesis. In this work, the synthesis and complete characterization of the first covalently linked porphyrin‐cobalt diimine‐dioxime dyad (ZnP‐Co) is reported. The synthetic procedure that was followed is based on simple and high yielding reactions, without using any noble metal. Photophysical investigation of the dyad revealed sufficient electronic communication between the sensitizer and the catalyst in the excited state. Finally, NiO films were sensitized with ZnP‐Co and the H2‐evolving photoelectrochemical activity of the resulting photocathode was assessed. The modest performances could be rationalized thanks to photolysis and post‐operando characterizations of the system, thus providing some guidelines toward the design of more efficient porphyrin‐based assemblies.

International audience; In the current work, we present the use of two free-base and two zinc-metallated porphyrin-ruthenium(II) polypyridine dyads, along with two reference porphyrin derivatives, as sensitizers in both n-and p-type DSSCs and DSPECs. Two of the dyads contain the well-known Ru(bpy)3 unit (HOOC-DMP-Ru(bpy)3 and HOOC-(Zn)DMP-Ru(bpy)3), while in the other two terpyridine-Ru(Cl)-bypiridine was used (HOOC-DMP-tpy-Ru and HOOC-(Zn)DMP-tpy-Ru). In all systems, the amide-bonding motif was utilized for the connection of the counterparts comprising each dyad. Photophysical investigation of the reported systems indicated sufficient electronic interactions for the dyads in their excited states (emission measurements). The photovoltaic measurements revealed that the presence of the ruthenium complex improves the overall performance of the dyads with the most efficient dyad being HOOC-(Zn)DMP-tpy-Ru in both n-and p-type DSSCs. Consequently, HOOC-(Zn)DMP-tpy-Ru was used to fabricate n-and p-DSPECs towards the oxidation of methoxy-benzyl alcohol and the reduction of CO2, respectively.

International audience; Exploring a catalytic reaction other than water oxidation at the photoanode of a photoelectrochemical cell is probably a key feature to more efficiently generate the electrons needed to produce solar fuels. In this framework, we describe herein the fabrication of a TiO2-based dye-sensitized photo-electrosynthesis cell (DSPEC) using a zinc porphyrin (ZnP) sensitizer and a 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) organo-catalyst that quite efficiently catalyzes light-driven oxidation of methoxybenzyl alcohol into aldehyde. Two dyads ZnP–TEMPO, differing by the anchoring group (carboxylic acid and hydroxamic acid) on ZnP, were prepared and their electrochemical, absorption, and emission properties were recorded and quantum chemical modeling was realized. The photovoltaic performances in dye-sensitized solar cells were first examined in order to optimize the dyeing conditions and compare the relative efficiencies of the compounds. The dyads substituted with TEMPO outperform the reference zinc porphyrin lacking TEMPO with a much higher Jsc and Voc. The photocatalytic properties after immobilization on TiO2 nanocrystalline films toward para-methoxy benzyl alcohol oxidation were explored in borate buffer and in an acetonitrile electrolyte. In borate buffer, the optimal pH was 8 and using dyad ZnP–TEMPO anchored with hydroxamic acid, para-methoxy benzaldehyde was selectively produced with an average photocurrent density of 200 μA/cm2, a Faradaic efficiency of 82%, a turnover number (TON) of 26, and a turnover frequency (TOF) of 47 h–1. In acetonitrile, in the presence of 0.1 M N-methyl-imidazole, the same dyad gives an average photocurrent density of about 100 μA/cm2, a Faradaic efficiency of 76%, a TON of 13, and a TOF of 24 h–1. The stability of the anchor is crucial in the acetonitrile electrolyte, where the dyad is quite soluble since only the dyad functionalized with hydroxamic acid is compatible with these organic solvent conditions. Overall, this study paves the way to the development of more efficient and probably more stable TiO2-based DSPECs for alcohol oxidation that could advantageously complement those devoted to water oxidation.

International audience; Nitrogen-doped carbon dots were used as photosensitizers for H2 evolution in the presence of a series of mononuclear thiosemicarbazone nickel complexes. The catalysts were designed to display different substituents at the para position of the phenyl rings. These chemical modifications tune the electron-donating abilities of the complexes and influence their capability to reduce protons into hydrogen. All photocatalytic experiments were performed in aqueous solution, using as sacrificial electron donor TCEP/Asc (1:1), 0.1 M each, at pH=5. The complex bearing the most electron-donating ligand with the dimethylamino (N(CH3)2) substituent behaves as the best catalyst in our series of photocatalytic systems with TONCAT = 148, under white led radiation for 30 h. Therefore, this noble metalfree system can effectively produce hydrogen in water and further chemical modification of the ligand will likely improve its production.

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In the present work a series of gadolinium porphyrin double deckers and the corresponding monoporphyrinate derivatives were investigated towards photocatalytic hydrogen evolution. The complexes were modified both on the meso- and on the beta- positions of the porphyrin macrocycle. The presence of the double decker was proved essential towards the photocatalytic activity since Gd(TPyP)2 exhibited the higher performance which was 13.8 mmolg-1h-1. A self-assembly investigation of the porphyrin derivatives revealed that different supramolecular architectures can be obtained by varying the solvent mixture and the peripheral substitution, however this did not affect the photocatalytic activity of the complexes.

In this study, a highly efficient photocatalytic H2 production system is developed by employing porphyrins as photocatalysts. Palladium and platinum tetracarboxyporphyrins (PdTCP and PtTCP) are adsorbed or coadsorbed onto TiO2 nanoparticles (NPs), which act as the electron transport medium and as a scaffold that promotes the self-organization of the porphyrinoids. The self-organization of PdTCP and PtTCP, forming H- and J-aggregates, respectively, is the key element for H2 evolution, as in the absence of TiO2 NPs no catalytic activity is detected. Notably, J-aggregated PtTCPs are more efficient for H2 production than H-aggregated PdTCPs. In this approach, a single porphyrin, which self-organizes onto TiO2 NPs, acts as the light harvester and simultaneously as the catalyst, whereas TiO2 serves as the electron transport medium. Importantly, the concurrent adsorption of PdTCP and PtTCP onto TiO2 NPs results in the most efficient catalytic system, giving a turnover number of 22,733 and 30.2 mmol(H2 ) g(cat)-1 .

In this work a peptide nucleic acid (PNA) was covalently connected with two different chromophores, namely porphyrin and boron-dipyrromethene. To the best of our knowledge, this is the first example in the literature where a PNA unit is covalently linked to such chromophores. The self-assembly properties of the hybrids were examined through electron microscopy experiments by adopting the "good-bad" solvent self-assembly protocol. For both hybrids (PNA-TPP and PNA-BDP) we were able to observe distinctive supramolecular architectures. During these studies we investigated the influence of the solvent system, the concentration and the deposition method on the morphology of the formed nanostructures. In the case of PNA-TPP under all examined conditions well-formed nanospheres were obtained. Interestingly, in the PNA-BDP hybrid by simply altering the solvent mixture, self-assemblies of two different morphologies were formed (spherical and flake shaped). Absorption and emission studies suggested the formation of J-aggregates in all the obtained nanostructures. The nano-architectures assembled by PNA conjugates are capable of light-harvesting and producing hydrogen using Pt nanoparticles as a photocatalyst.

A supramolecular triad composed of a fused zinc phthalocyanine-free-base porphyrin dyad (ZnPc-H2 P) coordinated to phenylimidazole functionalized C60 via metal-ligand axial coordination was assembled, as a photosynthetic antenna-reaction centre mimic. The process of self-assembly resulting into the formation of C60 Im:ZnPc-H2 P supramolecular triad was probed by proton NMR, UV-Visible and fluorescence experiments at ambient temperature. The geometry and electronic structures were deduced from DFT calculations performed at the B3LYP/6-31G(dp) level. Electrochemical studies revealed ZnPc to be a better electron donor compared to H2 P, and C60 to be the terminal electron acceptor. Fluorescence studies of the ZnPc-H2 P dyad revealed excitation energy transfer from 1 H2 P* to ZnPc within the fused dyad and was confirmed by femtosecond transient absorption studies. Similar to that reported earlier for the fused ZnPc-ZnP dyad, the energy transfer rate constant, kENT was in the order of 1012 s-1 in the ZnPc-H2 P dyad indicating an efficient process as a consequence of direct fusion of the two π-systems. In the presence of C60 Im bound to ZnPc, photoinduced electron transfer leading to H2 P-ZnPc.+ :ImC60.- charge separated state was observed either by selective excitation of ZnPc or H2 P. The latter excitation involved an energy transfer followed by electron transfer mechanism. Nanosecond transient absorption studies revealed that the lifetime of charge separated state persists for about 120 ns indicating charge stabilization in the triad.

Here, we use a simple and effective method to accomplish energy level alignment and thus electron injection barrier control in organic light emitting diodes (OLEDs) with a conventional architecture based on a green emissive copolymer. In particular, a series of functionalized zinc porphyrin compounds bearing π-delocalized triazine electron withdrawing spacers for efficient intramolecular electron transfer and different terminal groups such as glycine moieties in their peripheral substitutes are employed as thin interlayers at the emissive layer/Al (cathode) interface to realize efficient electron injection/transport. The effects of spatial (i.e., assembly) configuration, molecular dipole moment and type of peripheral group termination on the optical properties and energy level tuning are investigated by steady-state and time-resolved photoluminescence spectroscopy in F8BT/porphyrin films, by photovoltage measurements in OLED devices and by surface work function measurements in Al electrodes modified with the functionalized zinc porphyrins. The performance of OLEDs is significantly improved upon using the functionalized porphyrin interlayers with the recorded luminance of the devices to reach values 1 order of magnitude higher than that of the reference diode without any electron injection/transport interlayer.

Motivated by the excellent electron-transfer capability of porphyrin molecules in natural photosynthesis, we introduce here the first application of a porphyrin compound to improve the performance of planar perovskite solar cells. The insertion of a thin layer consisting of a triazine-substituted Zn porphyrin between the TiO2 electron transport layer and the CH3NH3PbI3 perovskite film significantly augmented electron transfer toward TiO2 while also sufficiently improved the morphology of the perovskite film. The devices employing porphyrin-modified TiO2 exhibited a significant increase in the short-circuit current densities and a small increase in the fill factor. As a result, they delivered a maximum power conversion efficiency (PCE) of 16.87% (average 14.33%), which represents a 12% enhancement compared to 15.01% (average 12.53%) of the reference cell. Moreover, the porphyrin-modified cells exhibited improved hysteretic behavior and a higher stabilized power output of 14.40% compared to 10.70% of the re...

We investigate a biomimetic model of a TyrZ /His190 pair, a hydrogen-bonded phenol/imidazole covalently attached to a porphyrin sensitizer. Laser flash photolysis in the presence of an external electron acceptor reveals the need for water molecules to unlock the light-induced oxidation of the phenol through an intramolecular pathway. Kinetics monitoring encompasses two fast phases with distinct spectral properties. The first phase is related to a one-electron transfer from the phenol to the porphyrin radical cation coupled with a domino two-proton transfer leading to the ejection of a proton from the imidazole-phenol pair. The second phase concerns conveying the released proton to the porphyrin N4 coordinating cavity. Our study provides an unprecedented example of a light-induced electron-transfer process in a TyrZ /His190 model of photosystem II, evidencing the movement of both the phenol and imidazole protons along an isoenergetic pathway.

In the present work, we effectively modify the TiO2 electron transport layer of organic solar cells with an inverted architecture using appropriately engineered porphyrin molecules. The results show that the optimized porphyrin modifier bearing two carboxylic acids as the anchoring groups and a triazine electron-withdrawing spacer significantly reduces the work function of TiO2, thereby reducing the electron extraction barrier. Moreover, the lower surface energy of the porphyrin-modified substrate results in better physical compatibility between the latter and the photoactive blend. Upon employing porphyrin-modified TiO2 electron transport layers in PTB7:PC71BM-based organic solar cells we obtained an improved average power conversion efficiency up to 8.73%. Importantly, porphyrin modification significantly increased the lifetime of the devices, which retained 80% of their initial efficiency after 500 h of storage in the dark. Because of its simplicity and efficacy, this approach should give tantalizing g...