Synthesis of a PPV-fluorene derivative: Applications in luminescent devices Paula C. Rodrigues, 1,2 * Bruno D. Fontes, 2 Bruno B. M. Torres, 1 Washington S. Sousa, 1 Greg  orio C. Faria, 1 Debora T. Balogh, 1 Roberto M. Faria, 1 Leni Akcelrud 2 1 Grupo de Pol  ımeros, IFSC, Universidade de S~ ao Paulo, S~ ao Carlos SP, Brazil 2 LaPPS, Universidade Federal do Paran a, Curitiba PR, Brazil *Present address: Departamento Acad^ emico de Qu  ımica e Biologia, DAQBi, Universidade Tecnol ogica Federal do Paran a, Curitiba, PR, Brazil Correspondence to: P. C. Rodrigues (E - mail: paulac@utfpr.edu.br) and R. M. Faria (E - mail: faria@ifsc.usp.br); L. Akcelrud (E - mail: leni@leniak.net) ABSTRACT: Synthesis of a polyfluorene/poly(p-phenylene vinylene) derivative, the Poly [(9,9 0 -di-hexylfluorenediylvinylene-alt-1,4-phe- nylenevinylene)-co-((9,9 0 -(3-t-butylpropanoate) fluorene-1,4-phenylene)] (LaPPS 42) was performed following Wittig and Suzuki routes. Polyfluorenes and derivatives have been used in electroluminescent devices, and the synthesis described here has the advantage in pave the way to get distinct structures having different emission spectra. An extensive study of its electrochemical, thermomechani- cal, optical, and structural properties was carried out, as well as its application in electroluminescent devices. Polymer light-emitting diodes (PLEDs) and polymer light-emitting electrochemical cells (PLECs) were built using LaPPS 42 as active layer, and their electric and optical characterizations confirm they have a potential as active element in electroluminescent devices. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42579. KEYWORDS: conducting polymers; photochemistry; properties and characterization Received 18 November 2014; accepted 4 June 2015 DOI: 10.1002/app.42579 INTRODUCTION High-efficiency organic light-emitting devices and low-cost pro- duction of flexible displays have encouraged the search for new luminescent polymer structures. A desirable polymer light- emitting device should have low operating voltage, high exciton generation efficiency and high power efficiency. Derivatives and copolymers of polyfluorene have been exten- sively used for electroluminescent devices mainly because it is possible to tune the emission of the active layer through a vari- ety of chemical modifications that can be introduced in the main chain. 1–5 Thus, modified polyfluorenes can cover a range of emission throughout the visible spectrum, exhibiting high electroluminescence efficiency, as well as good thermal and oxi- dative stabilities. Polymer light-emitting diodes (PLEDs) 6–8 and polymer light- emitting electrochemical cells (PLECs) 9–12 are two types of organic devices for applications in lighting panels and screen displays. While PLEDs operate as single diodes whose perform- ance depend on the bias polarity and on the work function of the electrodes, PLECs can light in both voltage polarities and do not depend on the characteristics of the electrodes. 10 These dif- ferences comes from the fact that in a LED the active region is a single layer of a luminescent polymer; in PLECs, on the other hand, the active layer is made by blending an electronic lumi- nescent polymer with an ionic conducting polymer and a tri- flate salt. 10–12 Another difference resides in the mechanism of recombination and light emission. In PLEDs exciton recombina- tion can occur throughout the length of the active layer; in PLECS, recombination occurs in a thin insulator region (pin junction) within the active layer, formed by p and n electro- chemical doping. 10 One disadvantage of PLECs in comparison with PLEDs is the slow response caused by the low ionic mobility. The present article brings a contribution to the synthesis of the poly[(9,9 0 -di-hexylfluorenediylvinylene-alt-1,4-phenylenevinylene)- co-((9,9 0 -(3-t-butylpropanoate) fluorene-1,4-phenylene)] (LaPPS 42), which is a copolymer based on fluorene and phenyleneviny- lene, and its application as the active layer in PLEDs and PLECs. The chemical route for the material’s preparation followed the Wittig and Suzuki polycondensations, and an extensive study of its electrochemical, thermal and V C 2015 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2015, DOI: 10.1002/APP.42579 42579 (1 of 8)