Narcissistic self-sorting in Zn(II) porphyrin derived semiconducting nanostructures.

The narcissistic self-sorted phenomenon is explicitly attributed to the structural similarities in organic molecules. Although such relevant materials are rarely explored, self-sorted structures from macrocyclic π-conjugated-based p- and n-type organic semiconductors facilitate the increase of exciton dissociation and charge separation in bulk heterojunction solar cells. Herein, we report two extended π-conjugated derivatives consisting of zinc-porphyrin-linked benzothiadiazole acting as an acceptor (PB) and anthracene as a donor (PA). Despite having the same porphyrin π-conjugated core in PA and PB, variations in donor and acceptor moieties make the molecular packing form one-dimensional (1D) self-assembled nanofibers via H- and J-type aggregates. Interestingly, a dissimilar aggregate of PA and PB exists as a mixture (PA + PB), promoting narcissistic self-sorted structures. Electrochemical impedance investigation reveals that the electronic characteristics of self-sorting assemblies are influenced by the difference in electrostatic potentials for PA and PB, resulting in a transitional electrical conductivity of 0.14 S cm-1. Therefore, the design of such materials for the fabrication of effective photovoltaics is promoted by these extraordinary self-sorted behaviors in comparable organic π-conjugated molecules.

Investigating the role of corrole as an excitation energy relay in light-induced processes in closely connected N,N'-bis(biphenyl-4-yl)aniline functionalized corrole donor-acceptor dyad.

A photosynthetic antenna-reaction center model, BBA-PFCor comprised of N,N'-bis(biphenyl-4-yl)aniline (BBA) covalently functionalized to bis(pentafluoro)corrole moiety has been prepared and the contribution of the BBA as the photoinduced energy transfer antenna was investigated. UV-visible studies have shown that integrating the electron-rich BBA chromophore into the corrole core has broadened the soret band of the corrole moiety with the absorption spanning from 300 to 700 nm. Electrochemical studies, in corroboration with the computational calculations, revealed that, BBA moiety can act as an electron reservoir and, in the excited state, it would transfer the excited energy to the corrole moiety in the dyad. Steady-state fluorescence studies have demonstrated that, upon photoexcitation of the BBA moiety of BBA-PFCor at 310 nm in solvents of varied polarity, the BBA emission centered at 400 nm was observed to be quenched, with the concomitant appearance of the corrole emission from 500 to 700 nm, indicating the happening of photoinduced energy transfer (PEnT) from 1BBA* to corrole moiety. Parallel control experiments involving the excitation of the corrole moiety at 410 nm did not result in the diminishing of the corrole emission, suggesting that the quenching of the BBA emission in BBA-PFCor is majorly due to intramolecular PEnT from 1BBA* to corrole moiety leading to the formation of singlet excited corrole, that is, 1BBA*-PFCor ➔ BBA-1PFCor*. The free energy changes of PEnT, ΔGEnT, were found to be thermodynamically feasible in all the solvents used for the study. Parallel time-resolved fluorescence studies were congruent with the steady-state fluorescence results and provided further evidence for the occurrence of ultrafast PEnT from 1BBA*➔corrole in the dyad with the rates of energy transfer (kEnT) of ~108 s-1.

Glucocorticoid receptor mediated sensitization of colon cancer to photodynamic therapy induced cell death.

Photodynamic therapy (PDT) is a clinically approved, non-invasive alternate cancer therapy. A synthetic glucocorticoid (GC), dexamethasone (Dex) has previously been demonstrated to sensitize cancer cells to chemotherapy. However, to the best of our knowledge, the sensitization effect of GCs on PDT has not yet been investigated. We hypothesized that glucocorticoid receptor (GR) targeting can selectively make cancer cells more sensitive to PDT treatment, as PDT induces hypoxia wherein GR-activity gets enhanced. In addition, Dex was reported to act against the PDT-induced cell survival pathways like HIF-1α, NRF2, NF-κB, STAT3 etc. Thus, both the treatments can complement each other and may result in increasing the effectiveness of combination therapy. Hence, in this study, we developed liposomal formulations of our previously reported PDT agent P-Nap, either alone (D1P-Nap) or in combination with Dex (D1XP-Nap) to elucidate the sensitization effect. Interestingly, our RT-PCR results in hypoxic conditions showed down-regulation of HIF-1α and over expression of GR-activated genes for glucose-6-phosphatase (G6Pase) and PEPCK enzymes, indicating prominent GR-transactivation. We also observed higher phototoxicity in CT26.WT cells treated with D1XP-Nap PDT under hypoxic conditions as compared to normoxic conditions. These effects were reversed when cells were pre-treated with RU486, a competitive inhibitor of GCs. Moreover, our in vivo findings of subcutaneous tumor model of Balb/C mice for colon cancer revealed a significant decrease in tumor volume as well as considerable enhancement in the survivability of PDT treated tumor-bearing mice when Dex was present in the formulation. A high Bax/Bcl-xL ratio, high p53 expression, enhanced E-cadherin expression and down-regulation of pro-tumorigenic transcription factors NF-κB and c-Myc were found in tumor lysates from mice treated with D1XP-Nap under PDT, indicating GR-mediated sensitization of the tumor to PDT-induced cell death and enhancement of life-span for tumor bearing mice.

Intramolecular Photoinduced Energy and Electron Transfer Reactions in Phenanthroimidazole-Boron Dipyromethane Donor-Acceptor Dyads.

Donor-acceptor systems in which a donor phenanthroimidazole (PhI) is directly connected to a BODIPY acceptor (Dyad1) and separated by an ethynyl bridge between PhI and BODIPY (Dyad2) have been designed, synthesized, and characterized by various spectroscopic and electrochemical techniques. Optical absorption and 1H NMR characteristics of both dyads with those of constituent individuals suggest that there exists a minimum π-π interaction between phenanthroimidazole and BODIPY. Quenched emission of both the dyads was observed when excited either at phenthaoimidazole absorption maxima or at BODIPY absorption maxima in all three investigated solvents. The detailed spectral analysis provided evidence for an intramolecular photoinduced excitation energy transfer (PEnT) from the singlet excited state of phenanthroimidazole to BODIPY and photoinduced electron transfer (PET) from the ground state of phenanthroimidazole to BODIPY. Transient absorption studies suggest that charge-separated species (PhI•+ - BODIPY•-) are generated at a rate constant of (1.16 ± 0.01) × 108 s-1 for the dyads Dyad1 and (5.15 ± 0.03) × 108 s-1 and for Dyad2 whereas energy transfer rate constants were much higher and were on the order of (1.1 ± 0.02) × 1010 s-1 and (1.6 ± 0.02) × 1010 s-1 for Dyad1 and Dyad2, respectively, signifying their usefulness in light energy harvesting applications.

Multichromophore Integrated Panchromatic Azaborondipyrromethenes: Synthesis, Characterization, and Exploring the Role of AzaBODIPY as an Energy and Electron Relay in Photoinduced Processes.

Panchromatic azaborondipyrromethenes directly connected with N,N-ditolylaniline (TPA) and naphthalene (Naph) at 1,7- and/or 3,5-positions of the azaBODIPY platform, 1, 2, and 3, were synthesized and the roles of the individual chromophore constituents in the photo-induced energy and electron transfer processes have been investigated. Optical absorption studies have indicated that integrating the complementary absorbers, naphthalene and TPA moieties, into the azaBODIPY core yielded broad-band capturing dyes with the absorption ranging from 250-1000 nm. Parallel electrochemical studies revealed that TPA moiety in 1 and 2 is easier to oxidize when compared to azaBODIPY moiety, which are in congruent with the computational studies indicating that TPA moiety would behave as an electron donor and azaBODIPY as an acceptor in PET processes. Steady-state fluorescence studies indicated that the photo-excitation of the TPA moiety in 2 resulted in the occurrence of PET from 1 TPA* to azaBODIPY generating (TPA)2 + ⋅-(azaBODIPY)- ⋅ while that of naphthalene in 3 resulted in PEnT from 1 (naphthalene)* to azaBODIPY forming (Naph)2 -1 (azaBODIPY)*. Interestingly, in 1, excitation of naphthalene moiety resulted in sequential PEnT from 1 (naphthalene)* to azaBODIPY followed by the PET from TPA to 1 (azaBODIPY)* generating a charge-separated state, (TPA)2 + ⋅-(azaBODIPY)- ⋅-(Naph)2 Fluorescence lifetime studies have indicated that the electron and energy transfer processes occurred in nanosecond time scales.

Potentiation of novel porphyrin based photodynamic therapy against colon cancer with low dose doxorubicin and elucidating the molecular signalling pathways responsible for relapse.

Photodynamic therapy (PDT) is a promising non-invasive treatment modality for cancer and can be potentiated by combination with chemotherapy. Here, we combined PDT of novel porphyrin-based photosensitizers with low dose doxorubicin (Dox) to get maximum outcome. Dox potentiated and showed synergism with PDT under in vitro conditions on CT26.WT cells. The current colon cancer treatment strategies assure partial or even complete tumour regression but loco-regional relapse or distant metastasis is the major cause of death despite combination therapy. The spared cells after the treatment contribute to relapse and it is important to study their behaviour in host environment. Hence, we developed relapse models for PDT, Dox and combination treatments by transplanting respectively treated equal number of live cells to mice (n = 5) for tumour formation. Most of the treated cells lost tumour forming ability, but some treatment resistant cells developed tumours in few mice. These tumours served as relapse models and Western blot analysis of tumour samples provided clinically relevant information to delineate resistance strategies of individual as well as combination therapies at molecular level. Our results showed that low dose Dox helped in increasing the tumour inhibiting effect of PDT in combination therapy, but still there are indeed possibilities of relapse at later stages due to chemoresistance and immune suppression that may occur post-treatment. We observed that the combination therapy may also lead to the development of multidrug resistant (MDR) phenotype during relapse. Thus, this study provided clinically relevant information to further strengthen and improve PDT-drug combination therapy in order to avoid relapse and to treat cancer more effectively.

Phenothiazine functionalized fulleropyrrolidines: synthesis, charge transport and applications to organic solar cells.

A series of phenothiazine-C60/70 dyads containing fulleropyrrolidine tethered to C-3 position (C60-PTZ and C70-PTZ) or to the heteroatom N-position via either phenyl (C60-Ph-PTZ and C70-Ph-PTZ) or phenoxyethyl linkers (C60-PhOEt-PTZ and C70-PhOEt-PTZ) of the phenothiazine were synthesized and light-induced electron transfer events were explored. Optimized studies suggested that the highest molecular orbital (HOMO) resides on donor phenothiazine moiety while lowest molecular orbital (LUMO) on the acceptor fulleropyrrolidine moiety of the dyads. Optical and electrochemical properties suggested no electronic communication between the donor and acceptor moieties in the ground state. However, steady-state emission studies in solvents of varied polarity, involving selective excitation of C60/C70, disclosed that the emission intensity of C60/C70 was quenched in the dyads in the increasing order, C60/70-PTZ > C60/70-Ph-PTZ > C60/70-PhOEt-PTZ as a consequence of the donor-acceptor distance resulted due to spacer lengths. Also, the emission quenching is more pronounced in polar solvents such as DMF compared to a non-polar solvent, toluene. With the support of parallel electrochemical studies, the emission quenching is attributed to intramolecular photo-induced electron transfer occurring from PTZ to (C60/C70)* generating a radical ion pair, PTZ+⋅-C60-⋅/PTZ+⋅-C70-⋅. Finally, bulk heterojunction (BHJ) solar cells devices inverted fashion prepared by employing the dyads as acceptors, and PTB7 as donor, suggested that the devices prepared from C70 derivatives i.e., PTB7:C70-PTZ and PTB7:C70-PhOEt-PTZ exhibited better power conversion efficiency of 2.66% and 2.15%, respectively over C60 derivatives i.e., PTB7:C60-PTZ and PTB7:C60-PhOEt-PTZ with the efficiencies of 1.80 and 1.72%, respectively. AFM studies revealed that the poor performance of PTB7:C60-PTZ- and PTB7:C60-PhOEt-PTZ-based devices can be ascribed to the lower solubility of the dyads in 1,2-DCB solvent leading to rough morphology.

2H-Pyrano[3,2-c]chromene-2,5(6H)-diones: Synthesis, Characterization, Photophysical and Redox Studies for Potential Optoelectronic Applications.

Herein, we report the preparation of 2H-pyrano[3,2-c]chromene-2,5(6H)-diones 3a-x by reacting 4-hydroxycoumarins 1a-b with Baylis-Hillman adducts 2a-w having electron releasing or electron withdrawing groups on benzyl ring of the pyranochromene moiety and study of their photophysical properties. The study of optical and electrochemical properties of the prepared compounds reveals that the electron releasing and electron withdrawing groups has not much impact on ground and excited state electronic behavior on pyranochromene moiety. The density functional theory suggests the highest occupied molecular orbital and lowest unoccupied molecular orbitals spread on coumarin moiety of pyranochromene unit. Further, these compounds are thermally stable (up to 200 °C) and lead to blue or green emission that should facilitate the development of organic light emitting diodes (OLEDs).

Novel phosphorus(V) tetrabenzotriazacorroles: synthesis, characterization, optical, electrochemical, and femtosecond nonlinear optical studies.

A series of three novel tetrabenzotriazacorroles (TBCs) designed with an alkyl substituent tert-butyl group (TBC-tert), an electron donor phenothiazine group (TBC-PTZ) and an energy donor carbazole group (TBC-CBZ) on the peripheral position with phosphorus metal in the cavity have been synthesized. All three compounds were characterized using various spectroscopic techniques and we assessed their femtosecond third-order nonlinear optical (NLO) properties. TBCs exhibit the properties of both phthalocyanines and corroles as they are derived from parent phthalocyanines. The optical studies revealed a new band at ∼450 nm, which was absent in the parent phthalocyanine molecules, and all three compounds obeyed Beer-Lambert's law. Singlet-state quantum yields were measured in different solvents and were found to be in the range of 0.3 to 0.6 for TBC-tert, 0.21 to 0.25 in the case of TBC-PTZ and 0.31 to 0.41 for TBC-CBZ. Time-resolved fluorescence studies revealed lifetimes in the ns regime (typically few ns). The redox properties of the TBCs suggest that they are easier to oxidize and harder to reduce and exhibit multiple oxidation and reduction potentials. Using the Z-scan technique, the third-order NLO properties were investigated with kilohertz and megahertz repetition rate femtosecond pulses at 800 nm. We report the first observation of strong three-photon absorption in these molecules with coefficients of ∼10-22 cm3 W-2 (∼10-13 cm3 W-2) with kHz (MHz) repetition rate fs pulse excitation.

1D alignment of Co(II) metalated porphyrin-napthalimide based self-assembled nanowires for photocatalytic hydrogen evolution.

The splitting of water into hydrogen and oxygen under visible light is an emerging phenomenon in green energy technology. Nevertheless, selecting an appropriate photocatalyst is rather significant to enhance hydrogen production on a large scale. In this context, organic photocatalysts have received considerable attention owing to their larger surface area, control in diffusion adsorption, nanostructures and electronic properties. Herein, we have developed five either free base or transition metalated porphyrin-napthalimide based donor-acceptor systems (PN1-PN5) and studied their morphology, electronic properties and catalytic behaviour. Detailed studies suggest that the Co(II) substituent D-A system (PN2) displayed a well-aligned one-dimensional (1D) nanowire with high electrical conductivity promoting remarkable photocatalytic hydrogen production rate (18 mM g-1 h-1) when compared to that of porphyrin-based derivatives reported until now. Thus, these results propose to investigate diverse metalated π-conjugated materials as photocatalysts for hydrogen production.

Optical, Electrochemical, Third-Order Nonlinear Optical Investigations of 3,4,5-Trimethoxy Phenyl Substituted Non-Aqueous Phthalocyanines.

A new series of non-aqueous phthalocyanines having 3,4,5-trimethoxy phenyl group at peripheral positions in which the central cavity possessing Cu(II), Zn(II), and without metals has been synthesized, and its absorption, fluorescence (steady-state and excited state lifetimes), electrochemical, and third-order nonlinear optical (NLO) properties were evaluated. Absorption studies data suggest that all three phthalocyanines obey Beer-Lambert's law, and the redox properties indicate that both oxidation and reduction reactions are macrocyclic centered. The singlet quantum yields were measured in different solvents and were found to be in the range of 0.2-0.5 in the case of free-base, whereas it was in the range of 0.1-0.5 in zinc derivative, while the time-resolved fluorescence data revealed lifetimes of typically a few ns. The third-order NLO properties were investigated using the Z-scan technique with kilohertz (for retrieving true electronic nonlinearities) and megahertz repetition rate femtosecond pulses at 800 nm. Intensity-dependent Z-scan studies revealed robust NLO coefficients for solutions and thin films (two-photon absorption cross-sections of 9,300-57,000 GM) of these molecules suggesting a strong potential for optical switching, imaging, and optical limiting applications.

Phenothiazine functional materials for organic optoelectronic applications.

Phenothiazine (PTZ) is one of the most extensively investigated S, N heterocyclic aromatic hydrocarbons due to its unique optical, electronic properties, flexibility of functionalization, low cost, and commercial availability. Hence, PTZ and its derivative materials have been attractive in various optoelectronic applications in the last few years. In this prospective, we have focused on the most significant characteristics of PTZ and highlighted how the structural modifications such as different electron donors or acceptors, length of the π-conjugated system or spacers, polar or non-polar chains, and other functional groups influence the optoelectronic properties. This prospective provides a recent account of the advances in phenothiazine derivative materials as an active layer(s) for optoelectronic (viz. dye sensitized solar cells (DSSCs), perovskite solar cells (PSCs), organic solar cells (OSCs), organic light-emitting diodes (OLEDs), organic field-effect transistor (OFETs), chemosensing, nonlinear optical materials (NLOs), and supramolecular self-assembly applications. Finally, future prospects are discussed based on the structure-property relationship in PTZ-derivative materials. This overview will pave the way for researchers to design and develop new PTZ-functionalized structures and use them for various organic optoelectronic applications.

π-Conjugated Materials Derived From Boron-Chalcogenophene Combination. A Brief Description of Synthetic Routes and Optoelectronic Applications.

Functional materials composed of Boron-chalcogenophene conjugates have emerged as promising ensemble featuring commendable optoelectronic properties. This review describes the categories, synthetic routes and optoelectronic applications of a range of boron-chalcogenophene conjugates. Conjugation and linking of different types of tri- and tetra-coordinated boron moieties with chalcogenophenes have remained an important strategy for constructing a range of functional materials. Synthetic protocols have been devised to efficiently prepare such chemically robust conjugates, often exhibiting a myriad of photophysical properties, redox capabilities and also solid-state behaviors. Tin-boron and silicon-boron exchange protocols have been efficiently adapted to access these boron-chalcogenophenes. Few other commonly used methods namely, hydroboration of alkynes as well as electrophilic borylations are also mentioned. The chemical and electronic properties of such boron-chalcogenophene conjugates are directly influenced by the strong Lewis acid character of trivalent boranes which can further alter the intra- and inter- molecular Lewis acid-base interactions. Apart from the synthetic protocols, recent advances in the application of these boron-chalcogenophene conjugates towards analyte sensing, organic electronics, molecular switches and several other aspects will be discussed in this review.

Excitation-Wavelength-Dependent Light-Induced Electron Transfer and Twisted Intramolecular Charge Transfer in N,N-Bis(4'-tert-butylbiphenyl-4-yl)aniline Functionalized Borondipyrromethenes.

A series of bis(4'-tert-butylbiphenyl-4-yl)aniline (BBA) functionalized borondipyrromethene (BODIPY) dyads, Dyads 1-3, containing the BBA group tethered to BODIPY moiety either directly or through a phenyl or alkynyl phenyl spacers are synthesized, and the light-mediated charge transfer within the chromophores has been systematically investigated. The crystal structure of Dyad-1 showed a tilt of 44.2° between the BODIPY and BBA molecular planes and intermolecular C-H···π interactions with these moieties. Cyclic voltammetric and computational studies showed that the BBA moiety can act as the electron donor (D) and BODIPY as the electron acceptor (A) and the optical absorption studies revealed that an increase in the conjugation of the linker from Dyad-1 to Dyad-2 resulted in bathochromic shifts. Steady-state fluorescence studies involving photoexcitation of the BBA moiety at 326 nm resulted in the decrease in fluorescence intensity of the BBA, indicating the possibility of sequential occurrence of faster photoinduced energy transfer (PEnT) followed by the photoinduced electron transfer (PET) or solely PET within the dyads, and the driving forces of the charge separation were calculated to be exothermic in all of the employed solvents. Parallel time-resolved fluorescence experiments involving the excitation of BBA moiety also supported the occurrence of charge separation in these dyads. Interestingly, excitation of the BODIPY moiety of Dyad-1 and Dyad-2 at 490 nm in solvents of increasing polarity leads to a red-shifted BODIPY emission with weakened intensity. This spectral behavior indicated the occurrence of emission from the locally excited (LE) state in nonpolar solvents, whereas formation of an LE state followed by the rotation of the chromophores at the D-A bond leads to a low energy twisted intramolecular charge transfer state (TICT), resulting in a charge-separated state BBA+•-BODIPY-• in polar solvents. Furthermore, the hydrophobicity studies involving the solutions of dyads in admixtures of polar tetrahydrofuran (THF) and nonpolar hexanes revealed that when the fraction of hexanes in these mixtures is increased, the emission of BODIPY moiety was observed to be blue-shifted and exhibited enhanced intensity supporting the occurrence of TICT in these dyads.

Synthesis and Opto-electronic Properties of BODIPY o-OPhos Systems.

Herein, we report the versatile synthetic strategy and opto-electronic properties for the phosphorylation of BODIPY derivatives 5aa-5ak by substituting with an electron-donating/withdrawing group at the ortho position. Nevertheless, this new methodology relatively promotes the tolerance of the aldehyde moiety and the high yield for the synthesis of BODIPY o-OPhos derivatives. The photophysical studies suggest improved optical properties due to the inductive effect of various electron-donating/withdrawing groups. The UV-visible and the emission data suggest that BODIPY o-OPhos derivatives emphasize the property of the excited states with an increase in fluorescence intensity and high quantum yields due to the presence of bulky phospsho-triester at the meso- position which hinders the free rotation around the C-Ar bond and facilitates the development of OLEDs and various organophosphorus warfare agents. Electrochemical studies reveal 5ak depicts the ease of redox activity amongst the 5aa-5ak derivatives. The density functional theory indicates the highest occupied molecular orbital on the BODIPY moiety whereas the lowest unoccupied molecular orbital delocalized on BODIPY and the phospho-triester moieties. Thus, the unique development of the novel BODIPY derivatives with improved optical and redox properties pave the way for fluorescent probes and bioimaging techniques.

Recent Progress and Emerging Applications of Rare Earth Doped Phosphor Materials for Dye-Sensitized and Perovskite Solar Cells: A Review.

Although the efficiency of Dye-sensitized and Perovskite solar cell is still below the performance level of market dominance silicon solar cells, in last few years they have grabbed significant attention because of their fabrication ease using low-cost materials, and henceforth these cells are considered as a promising alternative to commercial photovoltaic devices. However, third generation solar cells have significant absorption in the visible region of solar spectrum, which confines their power conversion efficiency. Subsequently, the performance of current photovoltaics is significantly hampered by the transmission loss of sub-band-gap photons. To overcome these issues, rare earth doped luminescent materials is the favorable route followed to convert these transmitted sub-band-gap photons into above-band-gap light, where solar cells typically have significant light-scattering effects. Moreover, the rare earth based down/up conversion material facilitates the improvement in sensitization, light-scattering and device stability of these devices. This review provides insight into the application of various down/up conversion materials for Dye-sensitized and perovskite solar cell applications. Additionally, the paper discusses the techniques to improve the photovoltaic performance in terms of current density and photo voltage in detail.

Metal-free propargylation/aza-annulation approach to substituted ß-carbolines and evaluation of their photophysical properties.

An efficient acid-catalyzed propargylation/aza-annulation sequence was developed under metal-free reaction conditions, thus leading to a one-pot synthesis of a variety of substituted ß-carbolines starting from propargylic alcohols and indole 2-carbonyls. This versatile strategy was further extended to the synthesis of 5-azaindoles and 5-azabenzothiazoles. Optical properties suggested that manipulation of electron donor and acceptor moieties on ß-carbolines has an impact on their ground and excited state electronic behavior. This leads to blue or green emission and should facilitate the development of organic light emitting diodes (OLEDs). Electrochemical and stability studies revealed that 4a-6 shows ease of redox activity and photostability during illumination.

MA2CoBr4: lead-free cobalt-based perovskite for electrochemical conversion of water to oxygen.

We have synthesized a lead-free stable organic-inorganic perovskite (MA2CoBr4) by using non-hazardous solvents such as methanol and ethanol, which are eco-friendly and safe to handle in comparison to DMF, toluene, etc. Single crystals of MA2CoBr4 were grown using a simple solution technique, and their electrochemical oxygen evolution was investigated in a wide pH range.

Metallated Macrocyclic Derivatives as a Hole - Transporting Materials for Perovskite Solar Cells.

Spiro-OMeTAD is widely used as thehole-transporting material (HTM) in perovskite solar cells (PSC), which extracts positive charges and protects the perovskite materials from metal electrode, setting a new world-record efficiency of more than 20 %. Spiro-OMeTAD layer engross moisture leading to the degradation of perovskite, and therefore, has poor air stability. It is also expensive therefore limiting scale-up, so macrocyclic metal complex derivatives (MMDs) could be a suitable replacement. Our review covers low-cost, high yield hydrophobic materials with minimal steps required for synthesis of efficient HTMs for planar/mesostructured PSCs. The MMDs based devices demonstrated PCEs around 19 % and showed stability for a longer duration, indicating that MMDs are a promising alternative to spiro-OMeTAD and also easy to scale-up via solution approach. Additionally, this review describes how optical and electrical properties of MMDs change with chemical structure, allowing for the design of novel hole-mobility materials to achieve negligible hysteresis and act as effective functional barriers against moisture which results in a significant increase in the stability of the device. We provide an overview of the apt green-synthesis, characterization, stability and implementation of the various classes of macrocyclic metal complex derivatives as HTM for photovoltaic applications.

Stipulating Low Production Cost Solar Cells All Set to Retail !

Today's solar cells are exceptionally in demand whilst excess exploitation of natural fossil fuels. In this context, the first and second generation solar cells commercially available in market for more than decades however limitations in production cost and large-scale applications insist to generate inexpensive materials for fabrication. Thereby, organic materials based solar cells explored and emerging as third generation solar cells which possess flexibility, low cost and large-scale applications. For example, organic photovoltaics, dye sensitized solar cells and perovskite (organic-inorganic) solar cells (PSCs) are considered third generation solar cells wherein PSCs reached the record power conversion efficiency (PCE ∼23 %) and durability assists great advantages for commercialization in near future. Moreover, we reported various global renowned companies involved producing the modules and materials for three generation solar cells, hence, majority of companies considered commercialization of perovskite based solar cells assist low cost photovoltaics to meet the current energy necessities and environmental safety.