<title>Tuning the electroluminescence and photoluminescence of PPV derivatives by protonation-deprotonation processes</title>

Abstract

The preparation and optical characterization of a novel PPV derivative displaying reversible tunable photophysical and electrophysical properties, poly-(5-vinylene-5'-(vinylene-1 ,4-phenylene)-2,2'-bipyridine), p-BVP, (1), is reported and its application in the preparation of tunable organic electroluminescent devices is described. The photophysical properties of the new polymer, such as its absorption, emission and electroluminescence are sensitive to the presence of even minute traces of vapors of different acids and bases such as ammonia, formic acid and haloacids. The acid/base vapor induced optical changes are reversible and can be repeated many times without any significant degradation of the optical and mechanical properties of the films. Intermediate spectra can be generated simply by controlling the exposure time of the films to acidic or basic vapors. Similar effects were observed for two other polymers, poly-(5-vinylene-5'tri-(vinylene-1 ,4-phenylene)-2,2'-bipyridme), p-BTYP, (2), and its random analog p-BRTVP, (3). The tunability of the photo-and electrophysical properties of the polymers originates probably from structural (intra-and mterstrand) changes associated with protonation-deprotonation processes and aggregation phenomena.

Synthesis of Light-Emitting Conjugated Polymers for Applications in Electroluminescent Devices

“…813 Copolymer 363a shows orange-red PL (λ max ) 580 nm) and EL (λ max ) 585 nm). 814 Protonation with gaseous HCl enables the PL emission to be reversibly red-shifted up to 90 nm depending on the concentration of HCl. The PL of 364 (λ max ) 578 nm) and 365 (λ max ) 582 nm) also show similar red-shifts (λ max ) 627 and 635 nm, respectively) upon protonation.…”

“…It is soluble only in acidic solvents and shows green-yellow PL (λ max = 566 nm). Alternating copolymers such as 363 − 364 and a random copolymer 365 with phenylene vinylene units have been made by Wittig coupling. , Copolymer 363b is soluble in standard solvents and shows red emission (λ max = 610 nm), which can be red-shifted up to 80 nm by protonation with formic acid . Copolymer 363a shows orange-red PL (λ max = 580 nm) and EL (λ max = 585 nm) .…”

“…Alternating copolymers such as 363 − 364 and a random copolymer 365 with phenylene vinylene units have been made by Wittig coupling. , Copolymer 363b is soluble in standard solvents and shows red emission (λ max = 610 nm), which can be red-shifted up to 80 nm by protonation with formic acid . Copolymer 363a shows orange-red PL (λ max = 580 nm) and EL (λ max = 585 nm) . Protonation with gaseous HCl enables the PL emission to be reversibly red-shifted up to 90 nm depending on the concentration of HCl.…”