Photodynamics of an aluminum(iii) porphyrin-phosphorous(v) porphyrin heterodimer reveals initial formation of a singlet CT state which relaxes to a high-energy triplet CT state lasting for about 105 μs.

The effect of utilizing a pure cis-α-dimethoxy carbonyl fulleropyrrolidine C70 (DMEC70) isomer as the electron transporting material (ETM) in inverted perovskite solar cells (PSCs) was evaluated. The as-prepared C70 mono-adduct products are mixtures of regioisomers and the interest was to evaluate them independently as ETMs. Three different cis-DMEC70 isomers (α, β-endo and β-exo) (mix-DMEC70) were synthesized and purified by HPLC. It was found that PSCs based on the pure α-DMEC70 exhibit a substantially enhanced maximum power conversion efficiency (PCE) of 18.6% as compared to devices based on the mixed-DMEC70 isomers that yielded a PCE of 16.4%. A maximum PCE of 15.7% was observed for devices based on [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). This work points out the importance of using pure fullerene derivative isomers as ETMs to reduce the intrinsic energy disorder, which enhances the overall device performance.

A series of carbazole (CBZ)–boron dipyrromethene (BODIPY) based donor–acceptor dyads, CB1, CB2, and CB3, with CBZ as an energy donor, tethered together with spacers of varied sizes i.e., phenyl bridge, biphenyl bridge and diphenylethyne bridge, respectively, are reported.

In supramolecular reaction center models, the lifetime of the charge-separated state depends on many factors. However, little attention has been paid to the redox potential of the species that lie between the donor and acceptor in the final charge separated state. Here, we report on a series of self-assembled aluminum porphyrin-based triads that provide a unique opportunity to study the influence of the porphyrin redox potential independently of other factors. The triads, BTMPA-Im→AlPorF n -Ph-C 60 (n = 0, 3, 5), were constructed by linking the fullerene (C 60 ) and bis(3,4,5-trimethoxyphenyl)aniline (BTMPA) to the aluminum(III) porphyrin. The porphyrin (AlPor, AlPorF 3 , or AlPorF 5 ) redox potentials are tuned by the substitution of phenyl (Ph), 3,4,5-trifluorophenyl (PhF 3 ), or 2,3,4,5,6-pentafluorophenyl (PhF 5 ) groups in its meso positions. The C 60 and BTMPA units are bound axially to opposite faces of the porphyrin plane via covalent and coordination bonds, respectively. Excitation of all of the triads results in sequential electron transfer that generates the identical final charge separated state, BTMPA •+ -Im→AlPorF n -Ph-C 60•− , which lies energetically 1.50 eV above the ground state. Despite the fact that the radical pair is identical in all of the triads, remarkably, the lifetime of the BTMPA •+ -Im→AlPorF n -Ph-C 60 •− radical pair was found to be very different in each of them, that is, 1240, 740, and 56 ns for BTMPA-Im→AlPorF 5 -Ph-C 60 , BTMPA-Im→AlPorF 3 -Ph-C 60 , and BTMPA-Im→AlPor-Ph-C 60 , respectively. These results clearly suggest that the charge recombination is an activated process that depends on the midpoint potential of the central aluminum(III) porphyrin (AlPorF n ).

Three, broad band capturing, vertically aligned reaction center models have been constructed using aluminum(iii) porphyrin.

As eries of chlorin-bacteriochlorin dyads (derived from naturallyo ccurring chlorophyll-a and bacteriochlorophyll-a), covalently connected either through the meso-aryl or b-pyrrolep osition (position-3) via an ester linkageh ave been synthesized and characterized as an ew class of far-red emittingf luorescence resonance energy transfer (FRET) imaging, and heavy atom-lacking singlet oxygen-producing agents.F rom systematic absorption, fluorescence, electrochemical, and computational studies, the role of chlorina s an energy donora nd bacteriochlorin as an energy acceptor in these wide-band-capturing dyads was established. Efficiency of FRET evaluated from spectralo verlap was found to be 95 and 98 %f or the meso-linked and b-pyrrole-linked dyads, respectively.F urthermore, evidence fort he occurrence of FRET from singlet-excited chlorint ob acteriochlorin was secured from studies involving femtosecond transient absorption studies in toluene. The measuredF RET rate constants, k FRET ,w ere in the order of 10 11 s À1 ,s uggesting the occurrenceo fu ltrafaste nergy transfer in these dyads. Nanosecondt ransienta bsorption studies confirmed relaxation of the energyt ransfer product, 1 BChl*, to its triplets tate, 3 Bchl*. The 3 Bchl* thus generated was capable of producing singleto xygen with quantumy ields comparablet ot heir monomeric entities. The occurrenceo fe fficient FRET emitting in the far-red region and the ability to produces inglet oxygen make the present series of dyads useful for photonic, imaging and therapy applications.

The synthesis of new C60 fullerene derivatives functionalized with thiophene moieties as well as with electron donating or electron withdrawing groups, bromine (Br) or cyano (CN), respectively, using Bingel reactions is reported. The synthesized derivatives were used as the electron transporting materials (ETMs) in inverted perovskite solar cells (PSCs). Compared to devices fabricated with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM), the new derivatives showed similar electrochemical properties and electron mobilities. However, PSCs based on the new derivatives synthesized in this work exhibited higher power conversion efficiencies (PCEs) than PC61BM based devices, which were ascribed to their better passivation ability, likely due to specific interactions between the fullerene addend and the perovskite layer surface. Devices based on the fullerene bearing the CN group exhibited an additionally improved efficiency due to the increased dielectric constant (εr) of this derivative. These results show that the new functionalized fullerene derivatives can act as efficient ETMs in inverted PSCs.

Directly linked to promote strong intramolecular interactions, donor–acceptor dyads and a donor–acceptor–donor triad featuring zinc phthalocyanine (ZnPc) as electron donor and perylenediimide (PDI) as electron acceptor have been synthesized and characterized. Owing to complementary absorption features of the entities, improved light absorption was witnessed in these conjugates. The optimized geometry and electronic structures showed the majority of the highest occupied molecular orbital (HOMO) on the ZnPc entity, whereas the lowest unoccupied molecular orbital (LUMO) was on the PDI entity, suggesting that the charge‐separated states would be ZnPc+–PDI.−. The electrochemical and free‐energy calculations suggested exothermic energy and/or electron transfer processes via the singlet states of PDI or ZnPc entities depending on the excitation wavelength of the laser used. The measured rates using femtosecond pump‐probe spectroscopy coupled with global analysis of transient data revealed ultrafast energy transfer from 1PDI* to ZnPc followed by charge separation. However, when ZnPc was selectively excited, only electron transfer was witnessed wherein the time constants for forward and reverse electron transfer processes followed Marcus predictions. The absorption in a wide section of the solar spectrum and the ultrafast charge separation suggest the usefulness of these systems as good photosynthetic models.