Kumar, Pankaj and Jain, S. C. and Kumar, Vikram and Chand, Suresh and Tandon, R. P.
(2008)
Trap filled limit and high current-voltage characteristics of organic diodes with non-zero Schottky barrier.
Journal of Physics D: Applied Physics, 41 (15).
pp. 155108-1.
ISSN 1361-6463
Abstract
The analytical expressions for trap filled limit voltage (V-TFL') and current - voltage characteristics for non- zero organic Schottky barrier are derived theoretically. The theoretical results are validated experimentally. In this case, the injected free charge carrier density at the contact is not infinitely large but a finite number p(0). For an exponential distribution of traps the maximum possible number of traps that can be filled in a sample is H-b' = H-b((p(0)/N-upsilon))(1/l), where l = T-c/T, T-c is the characteristic temperature of trap distribution. The use of Fermi - Dirac statistics causes a maximum error of only 6.9% in H-b'.The analytical expression for V-TFL' is shown to be V-TFL' = 0.5qH(b)'d(2)/epsilon epsilon(0), where d is the sample thickness. As the applied voltage increases and if p(0) > H-b', V-2 law is obtained over a considerable range of applied voltage. However, the curves change to Ohm's law as the voltage increases beyond this range. If p(0) < H-b', V-2 law is not obtained and the curves directly go to Ohm's law. Experimental results of ITO/PEDOT : PSS/poly(2-methoxy-5-2-ethyhexyloxy) 1,4-phenylenevinylene)(MEH-PPV)/Au and ITO/PEDOT : PSS/poly(3-hexylthiophene)(P3HT)/Au Schottky diodes are reported. The experimental results show excellent agreement with the theory.
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