Charge transport through conducting organic poly(2-methoxy-5(2-ethylhexyloxy)-1,4-phenylenevinylene)

Current-voltage ( J-V) characteristics of poly( 2-methoxy-5( 2-ethyhexyloxy)-1,4-phenylenevinylene)( MEH-PPV) have been studied in the hole-only devices ITO/PEDOT:PSS/MEH-PPV/Au, as a function of temperature from 300 to 98 K. Hole conduction in MEH-PPV has been well explained by an exponential trap-controlled drift model. In a considerable range of applied voltages, current obeys the power law J proportional to Vl+1, where l = T-c/T and T-c is the characteristic temperature of the exponential trap distribution. Assuming the effective density of states N-v = 2.7 x 10(18) cm(-3), the holes trap density ( H-b) and characteristic temperature ( T-c) have been calculated to be 1 x 10(18) cm(-3) and 550 K, respectively. As the voltage further increases current deviates and becomes smaller than J proportional to Vl+1. At low temperatures and sufficiently high-applied voltages, current follows the V-2 law. At higher temperatures slopes less than 2 of the log J-log V plots have been observed. The possible reasons for this behaviour are mentioned.