Structural and electrical properties of thermally evaporated cobalt phthalocyanine (CoPc) thin films

Abstract

Thin films of CoPc of various thickness have been deposited onto glass substrates using thermal evaporation technique at room temperature. The dark electrical resistivity measurements were carried out at different temperature range (298-423 K). An estimation of mean free path (0) of charge carriers in CoPc thin films and bulk resistivity, ρB was attempted. Measurements of thermoelectric power confirm that CoPc thin films behave as p-type semiconductors. The ac conductivity (σac) has been investigated in the frequency range (10 2-10 6 Hz) and temperature range (298-407 K). σac is found to be proportional to ω s where s ≈ 0.879 which is frequency and temperature independence. The ac conductivity interpreted by the correlated barrier hopping (CBH) model with centers of intimate valence alternation pairs type with a maximum barrier height, WM ≈ 1.594 eV.

Investigation of structural and optoelectronic properties of annealed nickel phthalocyanine thin films

“…In recent years, a large family of phthalocyanines (Pcs) such as CuPc [1], SnPc [2], PbPc [3], FePc [4], CoPc [5], MgPc [6] and ZnPc [7,8] have been studied extensively for potential optoelectronic applications. For certain advantages including ease of fabrication, thermal and chemical stability and insolubility in water, compatibility with flexible substrates and low-cost production processing, thin Pc films are commonly used in building electronic and optoelectronic devices such as organic solar cells [9,10], organic light emitting diodes (OLEDs) [11][12][13], field-effect transistors [14], optical recording [15], photodynamic therapy, non-linear optics [16], catalysis [17] and gas sensors [18].…”

Copper phthalocyanine based vertical organic field effect transistor with naturally patterned tin intermediate grid electrode

“…Mobility values for both electron and holes determined in CuPc field-effect transistors are available and widely spread [29e31], the same happening with mobility values measured applying other techniques [32,33]. Phthalocyanine, however, is frequently used as hole injection or transport layer [34], in part because phthalocyanines behave as ptype material due to absorbed oxygen which acts as an acceptor level in the band gap [35]. For this reason, it is more probable that the hole transport is preponderant in our devices when the drain is negatively biased.…”

Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate

“…dark current conditions before annealing process in temperature range of 216 K to 432 K within voltage range −5 V to +5 V. Fig. 6 shows current-voltage characteristics (I-V) of Au/CoPc/nSi/Al before and after annealing process obtained at room temperature [21]. The series resistance (R s ) and the shunt resistance (R sh ) are directly related to the device performance, determined from the plot of the junction resistance (R j ) against voltage where: which was determined from the current-voltage characteristics and R j plotted versus voltage.…”