Cho, J Char, K Kim, SY Hong, JD Lee, SK Kim, DY 2024-01-21T13:08:55Z 2024-01-21T13:08:55Z 2021-09-05 2000-12 0040-6090 https://pubs.kist.re.kr/handle/201004/140903 Multilayer electroluminescence (EL) devices based on the self-assembled layers of poly(p-phenylene vinylene) (PPV) and poly(sodium 4-styrenesulfonate) (PSS) were prepared and characterized. The increase of recombination region for the radiative decay of polaron excitons in the film device was achieved by two different fabrication methods: increase of the number of bilayers and increase of ionic strength of PSS solution using a salt additive. When simply increasing the number of bilayers, the relative device efficiency was improved proportional to the number of bilayers deposited. In contrast, the addition of NaCl salt to the PSS dipping solution resulted in higher thickness deposition but exhibited low luminescence level as well as low quantum efficiency. We believe that the decrease of the quantum efficiency, despite the increased thickness in the case of added salt in the PSS solution, is caused by the defect formation at the interface between PPV/PSS film and Al electrode. In order to minimize this problem, we inserted one insulating bilayer composed of cationic poly(allylamine hydrochloride) (PAH) and anionic poly(methacrylic acid) (PMA) in direct contact with the Al electrode. Upon this insertion, significant improvement of device efficiency was achieved and the quantum efficiency was shown to be proportional to the total film thickness even in the case of the salt addition scheme. (C) 2000 Elsevier Science B.V. All rights reserved. English ELSEVIER SCIENCE SA Effect of added ionic salt on the quantum efficiency of self-assembled films prepared with poly( p-phenylene vinylene) Article 10.1016/S0040-6090(00)01555-8 1 THIN SOLID FILMS, v.379, no.1-2, pp.188 - 194 THIN SOLID FILMS 379 1-2 188 194 N scie scopus 000166264900029 2-s2.0-0034513638 Materials Science, Multidisciplinary Materials Science, Coatings & Films Physics, Applied Physics, Condensed Matter Materials Science Physics Article LIGHT-EMITTING-DIODES POLY(P-PHENYLENE VINYLENE) ELECTROLUMINESCENCE HETEROSTRUCTURES INTERFACE SURFACES electrical properties and measurements electronic devices organic semiconductors surface defects