Contents lists available at ScienceDirect Synthetic Metals journal homepage: www.elsevier.com/locate/synmet Exploring the experimental photoluminescence, Raman and infrared responses and density functional theory results for TFB polymer Wesley Renzi a, ⁎ , Neusmar J.A. Cordeiro a , Henrique de Santana b , Marcello F. Costa a , Marco A.T. da Silva c , Edson Laureto a , José L. Duarte a a Department of Physics, State University of Londrina, Londrina, 86057-970, Brazil b Department of Chemistry, State University of Londrina, Londrina, 86057-970, Brazil c Department of Physics, Federal University of Technology - Paraná, Londrina, 86036-370, Brazil ARTICLE INFO Keywords: TFB DFT Spectroscopic characterization Photoluminescence Raman FT-IR ABSTRACT The density functional theory (DFT) simulation method has been highlighted in last years, due to its ability to predict optical, electronic and molecular properties of different materials, presenting good agreement with experimental results. In this work, we conducted a study of the structural and optical properties of the copolymer poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB) which appears with great emphasis in the literature being applied mainly as hole transporting and electron blocking layer in devices. Raman and FT-IR measurements were taken, and the obtained results were compared with those calculated via DFT method (DFT/B3LYP and 6–31g*). The comparison between experimental and DFT results were performed, and a good agreement between both results was observed, showing discrepancy lower than 7% for the vibra- tional peak positions, in energy. Also, photoluminescence (PL) measurements were performed at room and liquid nitrogen temperature. The PL spectra were reconstructed via Franck Condon, through the Huang-Rhys para- meters, by using the vibrational modes obtained both experimentally and via DFT. This procedure allowed to determine the contribution of the different vibrational modes to the photoluminescence vibronic bands. 1. Introduction The search for more efficient electroluminescent devices is one of the main topics currently addressed in the literature on Organic Light Emitting Diodes (OLEDs). The creation of new polymers and small molecules for OLED devices with high internal quantum efficiency (IQE) [1,2], the use of different device architectures[3], and the exploration of unusual proper- ties, like the thermally activated delayed fluorescence (TADF) [1,4,5] appear as great options to make more efficient devices. However, as im- portant as the study of the emission layers, the better understanding of the carriers transporting and/or blocking layers, such as TFB [6–8], ZnO [9,10], TPD [11], among others, are of great importance for the im- provement of these devices. The poly[(9,9-dioctylfluorenyl-2,7-diyl)-co- (4,4′-(N-(4-sec-butylphenyl)diphenylamine)], (TFB), is a fluorene copo- lymer, which appears with great emphasis in the literature on devices (OLEDs and OPVs). The use of thin layers of TFB as hole transporting and electron blocking layers proved to improve the device efficiency, reducing its operation voltage and current [12,13]. The semi-empirical computational simulation methods, Density Functional Theory (DFT) [14–16] and ab initio [17,18], have been shown to be of great importance in the determination of optical, elec- tronic and molecular properties of compounds. By working with the simulation parameters, it is possible to determine the properties of polymer chains with different conjugation lengths (mer), besides making possible the simulation of these chains surrounded by different solvents. Generally the simulations are performed considering isolated molecules, in vacuum, which presents good results in comparison to the experimental ones, for films. Due to the high quality of the simulations, they are, in general, enough for material characterization, although this situation should be evaluated in each case, because some materials present different chain conformations [19,20], depending on the sol- vent used. Taking into account the great applicability of the TFB in optoelec- tronic devices, and the insufficiency of studies aimed at the character- ization of its emissive properties, this work emphasizes the TFB basic optical characterization through data obtained both experimentally and via DFT, demonstrating the DFT effectiveness as an alternative for op- tical characterization of the material. In this work, photoluminescence https://doi.org/10.1016/j.synthmet.2017.12.008 Received 15 August 2017; Received in revised form 10 November 2017; Accepted 13 December 2017 ⁎ Corresponding author. E-mail address: renzi.wesley@gmail.com (W. Renzi). Abbreviations: DFT, density functional theory; PL, photoluminescence; FT-IR, fourier transform infrared Spectroscopy Synthetic Metals 236 (2018) 24–30 Available online 03 January 2018 0379-6779/ © 2017 Elsevier B.V. All rights reserved. T