Mol2Net-04 Electrical study of new anthracene derivatives for - PDF document

Mol2Net-04 , 2018 , BIOCHEMPHYS-01 (pages 1- x, type of paper, doi: xxx-xxxx http://sciforum.net/conference/mol2net-4 SciForum Mol2Net-04 Electrical study of new anthracene derivatives for electronics applications Ghada Attia*, Safa Teka, Mustaphe Majdoub, Rafik Ben Chaabane Laboratoire des Interfaces et des Matériaux Avancés (LIMA), Université de Monastir Faculté des Sciences de Monastir, Bd. de l’Environnement, 5019 Monastir, Tunisia. (S T.) safateka@gmail.com; (M.M.) mustapha.majdoub@fsm.rnu.tn; (R.B.C) rafik.benchaabane@fsm.rnu.tn * Author to whom correspondence should be addressed; Attia-Ghada@hotmail.com, Tel.: +33758846473 Received: / Accepted: / Published: Abstract: Due to the holes high transport mobility, anthracene derivates are widely used for the elaboration of OLEDs and other organic thin-layer-based electronic, such as transistors and photovoltaic cells. This study aims to investigate the electric properties of two new anthracene derivatives: 9-{[4- ({[4-(9 anthrylmethoxy)phenyl]sulfanyl}methyl)] methyl]anthracene (TDP-AN) and 4-(9- anthrylmethoxy) benzyl[4-(9-anthrylmethoxy)phenyl]sulfone (BPS-AN). The main difference between them is related to the functional group between the two central phenyls. Conductance measurements results show a frequency-independent behaviour, for low frequencies ranging between 0.1 and 100 KHz, while they exhibit a power law model for higher ones. BPS-AN was found more conductive than the TDP-AN. Impedance spectroscopy (IS) was then investigated to understand the charge carrier mechanisms in both TDP-AN and BPS-AN molecules. Measurements were carried out in the frequency range 100 Hz – 10 MHz at different bias voltages (from 0 V to 3 V). The obtained results agree with conductivity measurement ones. Keywords: Anthracene derivates; Conductance, Impedance spectroscopy, Charge carrier. 1. Introduction Organic semiconducting materials are very In this study we have chosen to investigate the attractive for electronic applications such as electric properties of two new anthracene organic thin-film transistors (OTFTs), organic derivatives: 9-{[4-({[4-(9 photovoltaic cells [1, 2] and organic light-emitting anthrylmethoxy)phenyl]sulfanyl}methyl)]methy] diodes (OLEDs). anthracene(TDP-AN) and 4-(9-anthrylmethoxy) Several organic monolayers have been benzyl[4-(9-anthrylmethoxy)phenyl]sulfone investigated for electronics applications. Our (BPS-AN). work concerns anthracene derivatives because of their multiple advantages, such as improved electrical conduction making them good materials for elaboration of organic diodes.

Mol2Net-04 , 2018 , BIOCHEMPHYS-01 (pages 1- x, type of paper, doi: xxx-xxxx . 2. Results and Discussion For conductance and impedance The dc conductance ( G dc ) remains constant at low measurements, each anthracene derivative was frequencies (0.1-100 kHz). Thus, a charge carrier placed between an aluminum (Al) cathode and a jumps from one position to its neighbouring tin oxide (ITO) anode (Figure. 1). The realized vacant one [3]. Beyond a critical frequency of structures were then characterized by impedance order of 100 kHz, the conductance starts to spectroscopy, a powerful technique for exploring increase. Consequently, a charge carrier will hop the charge carrier mechanisms in organic from a site to another one [3]. semiconductors. According to the conductance at 0V, obtained in Results gathered in Figure. 2c indicate that BPS-AN is more conductive than TDP-AN. +v -v 2.2 Parameters obtained by modeling the impedance spectra Cole-Cole representation for both devices at Anthracene Derivatives different bias voltages are shown in Figures.3a. (ITO) Glass substrate and 3b. The application of a voltage to the device, Figure. 1 . [ITO/ anthracene derivative/Al] diode structure results in a single semicircle whose radius decreases with increasing the bias from 0V to 3V. 2.1 The conductance measurements: The minimum value of Re (Z) (high frequency) The variation of conductance versus indicates the existence of voltage-independent frequency at different bias voltages for the two series resistance R s which corresponds to the realized devices is presented in Figures. 2a and 2b. ohmic contact with the interface holes-injecting These spectra present the steps performed in the ITO/organic material. The maximum value of Re frequency range 100 Hz – 10 MHz. Results (Z) (low frequency) represents the sum of R p indicate the presence of two parts, a quasi- parallel resistance with R s contact resistance. For constant conductance at low frequencies and an the both structures, the bulk resistance R p increase, according a power-law, for high ones. decreases with increasing bias. Besides, the conductance increases with the The obtained values, gathered in Figure 3c., applied bias voltage. indicate that ITO/BPS-AN/Al structure has a In general, the variation of conductance G lower resistance than that of ITO/TDP-AN/Al according to frequency in disordered materials one, in concordance with the conductivity obeys the relation: measurement results. G(ω) = G dc + G ac (ω) -5 10 ITO/TDP-AN/Al ITO/BPS-AN/Al ITO/BPS-AN/Al (a) (b) (c) 6' ITO/TDP-AN/Al -3 O O 6 S 10 6 6' 5 S 5' 0V 1 1' 5 0v 5' 7" 7" 1 1' 7" 7" 0,5V 6'' 8" 2 2' 8" 6" O 4 O 0.5v 6'' 4' 8" 2 2' 8" 6" 3 3' 1E-4 O 4 4' O 1V 3' 1v 3 9" 5" 5" 1,5V 9" 5" 9" 5" 1.5v 9" 10" 2V 1" 10" 1" Conductance(S) 2v 1" 10" Conductance(S) Conductance (S) 1" 10" 2,5V 2" 2.5v 2" 4" -4 4'' 10 2" 2" 4" 3V 3v 4'' 3" 3" 3" 3" 1E-5 -6 10 -5 10 1E-6 -6 10 -1 0 1 2 3 4 -3 -2 -1 0 1 2 3 4 10 10 10 10 10 10 10 10 10 10 10 10 10 10 0,01 0,1 1 10 100 1000 10000 Frequency (KHz) Frequency (KHz) Frequency (KHz) Figure 2. Conductance versus frequency at different applied bias voltages for (a) ITO/BPS-AN/Al, (b) ITO/TDP- AN/Al, (c) Superposition conductance versus frequency for the two devices at 0V.

Mol2Net-04 , 2018 , BIOCHEMPHYS-01 (pages 1- x, type of paper, doi: xxx-xxxx 4,0 6 (c) ITO/TDP-An/Al 2,0x10 (b) ITO/TDP-AN/Al ITO/BPS-AN/Al 0V 0V 0,4 (a) ITO/BPS-An/Al 5 0.5V 3,5 2,0x10 0.5V 1V 1V 1,5V 1.5V 6 1,6x10 2V 3,0 2V 2,5V C p 2.5V 0,3 5 1,5x10 3V 3V 2,5 R s 6 Rp [M.Ohm] Rp [M.Ohm] 1,2x10 -Im(Z)(  ) -Im(Z)(  ) 2,0 5 1,0x10 0,2 R p 5 8,0x10 1,5 4 5,0x10 0,1 1,0 5 4,0x10 0,5 0,0 0,0 0,0 0,0 0 6 6 6 6 0 5 5 5 5 5 1x10 2x10 3x10 4x10 0,0 0,5 1,0 1,5 2,0 2,5 3,0 1x10 2x10 3x10 4x10 5x10 Real(Z)(  ) Bias [Volt] Real(Z)(  ) Figure 3. Cole – Cole plots of complex impedance with variation of the bias voltage for (a) ITO/BPS-AN/Al, (b) ITO/TDP-AN/Al (c) Superposition of the bulk resistance R p at bias voltage for the both structures 3. Materials and Methods The anthracene-based organic materials were isopropanol successively and finally dried by a nitrogen gas flow. After this treatment, a 50 μl of synthesized via the Williamson reaction through the condensation of AnCl (9-(Chloromethyl) an anthracene molecule was used to form a thin anthracene) with two different bisphenols. Thus, film on the ITO substrate by the spin-coating with BPS (4,4′ the reaction of AnCl technique with a controlled speed of 2000 rpm. Finally, the obtained film was dried at 60 ° C for Sulfonyldiphenol) led to BPS-AN whereas TDP- AN was obtained from AnCl with TDP (4,4’ - 20 min to improve the adhesion between ITO and thiodiphenol). These anthracene-based semi- the anthracene layer. conducting materials were found to have good solubility in common organic solvents such as Impedance spectroscopy (IS) measurements, a tetrahydrofuran, chloroform, DMF and DMSO. powerful technique for exploring the charge carrier mechanisms in materials and mainly in Single-layer device was fabricated as sandwich organic semiconductors, have been recorded structures between an aluminum (Al) cathode and using HP 4192 LF impedance analyzer. an ITO anode (Fig 1.). ITO devices were cleaned for 20 min in an ultrasonic bath in acetone and . 4. Conclusions Two anthracene derivatives were synthesized and presented in this work: TDP-AN and BPS-AN. Conductance measurements show the existence of two regimes: constant conduction at low-frequencies, and a power-law behaviour at high ones. Also, conductance results indicate that BPS-AN is more conductive than TDP-AN. Cole – Cole plots were modelled to extract the suitable equivalent circuit: resistance in series with capacitance and resistance in parallel. From the fitted parameters, it appears that the bulk resistance decreases with the applied bias, and that BPS-AN molecule is more conductive than the TDP-An one. Conflicts of Interest: “The authors declare no conflicts of interest” References 1. H. Haikel, H. Khaled, J. Nejmeddine, R.B. Chaabane, S. Olivier, M. Mustapha, New anthracene-based soluble polymers: optical and charge carrier transport properties, J Polym Res 2013 , 20, 241-256. 2. H. Haikel, H. Khaled,M. Benzarti -Ghédira J. Nejmeddine, R.B. Chaabane, M. Mustapha, Optical and electrical characterization of thin films based on anthracene polyether polymers, Mater. Sci. Semicond. Process 2013 , 16, 851 – 858. 3. I. Zahou, R. Ben Chaabane, R. Mlika, S. Touaiti, B. Jamoussi, H. Ben Ouada, Optical and electrical properties of novel peripherally tetra and mono -quinoleinoxy substituted metallophtalocyanines, J Mater Sci: Mater Electron 2014 , 25, 2878 – 2888.