Structure influence of alkyl chains of thienothiophene-porphyrins on the performance of organic solar cells

Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.

An overview on AIEgen-decorated porphyrins:Current status and applications

One of the major obstacles of porphyrins is the aggregation-caused quenching(ACQ)of photoluminescence due to the strong intermolecularπ–πinteraction of the planar porphyrin core in the solid state.However,ACQ leads to the nonradiative deactivation of the photoexcited states which results in short-lived charge-separated states and thus low photoluminescence and singlet quantum yields.This phenomenon would limit the utilization of porphyrins in near-infrared fluorescent bioimaging,photodynamic therapy,photocatalytic hydrogen evolution,electrochemiluminescence,and chiroptical applications.Hence,to address the ACQ property of porphyrins and enhance the performance of the above applications,a limited number of AIEgen-decorated porphyrins have been designed,synthesized,and tested for their applications.It has been found that the introduction of AIEgens,such as tetraphenylethylene,diphenylacrylonitrile,(3,6-bis-(1-methyl-4-vinylpyridinium)-carbazole diiodide,and iridium motif into the porphyrin core,transformed the porphyrins from ACQ to aggregation-induced emission(AIE)in their solid state due to the reduced strong intermolecularπ–πstacking of porphyrins.Consequently,such porphyrins containing AIE features are employed as potential candidates in the above-mentioned applications.In this review,we summarize the AIEgen-decorated porphyrins which have been published to date,and also discuss the benefits of converting porphyrins from ACQ to AIE for enhanced performance within each application.As far as we know,there is no review that summarizes the structures and applications of AIEgen-decorated porphyrins to date.Therefore,we presume that this review would be helpful to design more efficient AIEgen-decorated porphyrins for a wide range of applications in the future.

Design of AIEgen-based porphyrin for efficient heterogeneous photocatalytic hydrogen evolution Special Collection:Aggregation-Induced Processes and Functions

Tetraphenylethylene(TPE)-conjugated porphyrin TPE-ZnPF is synthesized in high yield and characterized by single-crystal X-ray diffraction.The propeller-shaped TPE groups not only enable exceptional aggregation-induced emission(AIE)in the solid state but also abolish the strongπ-πstacking of porphyrin moieties and thus prohibit aggregation-caused quenching(ACQ).TPE-ZnPF aggregates feature longlived photoexcited states,which subsequently suppress non-radiative decay channels and enhance emission intensity.Moreover,its aggregates show more efficient lightharvesting ability due to the Förster resonance energy transfer from the TPE energy donor to the porphyrin core energy acceptor,well-defined nanosphere morphology,and more efficient photoinduced charge separation than the porphyrin Ph-ZnPF,which possesses ACQ and agglomerated morphology.As a result,an excellent photocatalytic hydrogen evolution rate(ηH_(2))of 56.20 mmol g^(‒1)h^(‒1)is recorded for TPE-ZnPF aggregates,which is 94-fold higher than that of the aggregates of Ph-ZnPF(0.60 mmol g^(‒1)h^(‒1))without the TPE groups.