Article Title

Large work function shift of organic semiconductors inducing enhanced interfacial electron transfer in organic optoelectronics enabled by porphyrin aggregated nanostructures

Authors

Maria Vasilopoulou, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece
Antonios M. Douvas, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece
Dimitra G. Georgiadou, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece
Vassilios Constantoudis, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece
Dimitris Davazoglou, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece
Stella Kennou, Department of Chemical Engineering, University of Patras, 26500 Patras, Greece
Leonidas C. Palilis, Departmen of Physics, University of Patras, 26500 Patras, Greece
Dimitra Daphnomili, Laboratory of Bioinorganic Chemistry, Chemistry Department, University of Crete, Voutes Campus, 71003 Heraklion, Crete, Greece
Athanassios G. Coutsolelos, Laboratory of Bioinorganic Chemistry, Chemistry Department, University of Crete, Voutes Campus, 71003 Heraklion, Crete, Greece
Panagiotis Argitis, Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research Demokritos, 153 10 Aghia Paraskevi Attikis, Athens, Greece

Keywords

porphyrins, OLEDs, OPVs, aggregates

Abstract

We report on large work function shifts induced by the coverage of several organic semiconducting (OSC) films commonly used in organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs) with a porphyrin aggregated layer. The insertion between the organic film and the aluminum cathode of an aggregated layer based on the meso-tetrakis(1-methylpyridinium-4-yl) porphyrin chloride (porphyrin 1), with its molecules adopting a face-to-face orientation parallel to the organic substrate, results in a significant shift of the OSC work function towards lower values due to the formation of a large interfacial dipole and induces large enhancement of either the OLED or OPV device efficiency. OLEDs based on poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,1’,3-thiadiazole)] (F8BT) and incorporating the porphyrin 1 at the cathode interface exhibited current efficiency values up to 13.8 cd/A, an almost three-fold improvement over the efficiency of 4.5 cd/A of the reference device. Accordingly, OPVs based on poly(3- hexylthiophene) (P3HT), [6,6]-phenyl-C61 butyric acid methyl ester (PC61BM) and porphyrin 1 increased their external quantum efficiencies to 4.4% relative to 2.7% for the reference device without the porphyrin layer. The incorporation of a layer based on the zinc meso-tetrakis (1-methylpyridinium-4-yl)porphyrin chloride (porphyrin 2), with its molecules adopting an edge-to-edge orientation, also introduced improvements, albeit more modest in all cases, highlighting the impact of molecular orientation.

Graphical Abstract

DOI

https://doi.org/10.1007/s12274-014-0428-9

Publisher

Tsinghua University Press

Recommended Citation

Maria Vasilopoulou,Antonios M. Douvas,Dimitra G. Georgiadou,Vassilios Constantoudis,Dimitris Davazoglou,Stella Kennou,Leonidas C. Palilis,Dimitra Daphnomili,Athanassios G. Coutsolelos,Panagiotis Argitis, Large work function shift of organic semiconductors inducing enhanced interfacial electron transfer in organic optoelectronics enabled by porphyrin aggregated nanostructures. NanoRes.2014, 7(5): 679–693