Optical and electrical properties of polycarbonate thin films grown by dip-coating method

W. Bala¹‘² K. Paprocki¹, M. Kuczkowska¹, P. Popielarski¹, K. Fabisiak¹, A. Korcala², K. Banach², Ł. Borszewski²,

¹Institute ofPhysics, Kazimierz Wielki University, Powstańców Wielkopolskich 2, PL 85-072

Toruń, Poland wbala @fizyka, umk.pl

Institute ofPhysics, N. Copernicus University, Grudziądzka 5/7, PL 87-100 Toruń, Poland

During the last years polymers based on carbazołe such as polycarbazole, poly(vinyl carbazole) (PVK) and poly(N-vinyl carbazole) and polycarbonate have attracted considerable attention due to their interesting physical properties followed by various technological applications in the area of electronics and optoelectronics [1-3].

The carbazole family forms a subset of the organie materials under study for blue organie light emitting diodes (OLED) and photovoltaic cells (PC) applications

A very promising family of materials that belongs to this category is the polycarbonate. Their good sensitivity to the solar spectrum combined with the high thermal, chemical and photochemical stability as well as their Iow cost makes polycarbonate derivatives strong candidates for futurę device applications especially in the area of photovoltaics (PV) where large area and cost-effective solar cells are reąuired. Over the past 20 years, polycarbonate based and a more generał organie PV celi has been the object of intense research efforts in numerous academic and industrial research laboratories. However, a very limited amount of information is available in scientific literaturę about the electrical properties of polycarbonate thin layers, especially as a function of temperaturę.

In this paper, we use the simple dip-coating techniąue to fabricate the polymer-based Schottky diodę. The polycarbonate layered structureswere fabricated on high-quality (1 0 0)-orientedn-type silicon and ąuartz substrates. We have investigated the optical and electrical properties of polycarbonate thin films deposited on silicon and ąuartz substrates by dip-coating method. The photoluminescence (PL), transmission (T) and reflection (R) spectra, current-voltage (I-V), capacitance-voltage (C-V) and charge deep-level transient spectroscopy (Q-DLTS) measurements have been made in the temperaturę rangę 100K-350K.

To explain their electrical behavior, the charge transport mechanism in organie semiconductor materials is a controversial topie, and no unified theory is available to explain the experimental results under different conditions to an acceptabłe degree of aceuracy [4]. We present a new method to extract the correct electrical characteristics in which the effects of the series resistance and the ideality factor have been taken into account. The method is based on the modified Norde function method combined with the conventional forward I-V method.

[1] D. Romero, M.Schaer, M. Leclerc, D. Ades, A. Siove, and Z. Zuppiroli, Synth. Met., 80, p. 271, 1996. [2] C. Chao and S. Chen Appl. Phys. Lett., vol. 73, p. 426, 1998.

[3] H. Meng, Z. Chen, W. Yu, J. Pei, X. Liu, Y. Lai, and W. Huang Synth. Met.,vól. 100, p. 297, 1999. [4] A. Chempbell, D. Bradley, and D. Lidzey, J. Appl. Phys., vol. 82,pp. 6326-6342, 1997.