Cryst. Res. Technol. 39, No. 1, 56 – 62 (2004) / DOI 10.1002/crat.200310149 © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Electrical, optical and photoconductive properties of Poly(dibenzo-18-crown-6) A. F. Qasrawi* 1 , A. Cihaner 1 , A. M. Önal 2 1 Department of Electrical and Electronics Engineering, Atilim University, Ankara, Turkey. 2 Department of Chemistry, Middle East Technical University, Ankara, Turkey. Received 15 April 2003, accepted 5 June 2003 Published online 15 January 2004 Key words polymers, thermal, hopping, conductivity, band gap, bimolecular, response time. PACS 73.61.Ng, 72.20.Dp, 72.20.Ee, 72.20.Jv, 72.30.+q To investigate the energy levels, absorption bands, band gap, dominant transport mechanisms, recombination mechanisms and the free carrier life time behavior of poly-dibenzo-18-crown-6, poly-DB18C6, films, the dark electrical conductivity in the temperature range of 200-550 K, the absorbance and photocurrent spectra, the photocurrent –illumination intensity and time dependence at 300 K were studied. The dark electrical conductivity measurements revealed the existence of three energy levels located at 0.93, 0.32 and 0.76 eV below the tails of the conduction band. The main transport mechanism in the dark was found to be due to the thermal excitation of charge carriers and the variable range hopping above and below 260 K, respectively. The photocurrent and absorbance spectra reflect a band gap of 3.9 eV. The photocurrent -illumination intensity dependence reflects the sublinear, linear and supralinear characters indicating the decrease, remaining constant and increase in the free electron life time that in turn show the bimolecular, strong and very strong recombination characters at the surface under the application of low, moderate and high illumination intensity, respectively. A response time of 25.6 s was calculated from the decay of I ph -time dependence. © 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Dibenzo-crown ethers are observed to undergo a specific trimerization on each aromatic ring leading to polytriphenylenes, where the triphenylene moieties are presumably two dimensionally linked by polyether bridges [1-3]. The structure of these poly(dibenzo-crown ethers) has been established by means of different physicochemical methods, such as scanning electron microscopy, infrared, UV-visible, EPR and solid state C- NMR spectroscopies [3]. Moreover, these polymers are conducting and ionophoric materials. Those materials have attracted attention during the last two decades [4]. Concerning ionophoric polymers, many of them have also been synthesized [5-10] and have found applications as solid supported reactants in phase transfer catalysis or membrane utilization like ion-exchange membranes, ion-selective electrodes or analogues of biological membranes. In addition, the influence of the complexing properties of polyether rings during and after the electropolymerization reaction has also been investigated for poly(dibenzo-crown ethers) [11]. Regarding these materials and the above mentioned applications, -up to our knowledge- no works have been investigated to consider their electrical and photoelectronic technological applications like, using these materials as memory cells, switching devices, photoconductors, radiation sensors, etc. These technological applications require the knowledge of the structural, optical, electrical, photoconduction and radiation properties of the material before subjecting it to instrumental designing. ____________________ * Corresponding author: e-mail: atef_qasrawi@atilim.edu.tr