Temperature dependence of carrier injection across organic heterojunctions

  1. Get@NRC: Temperature dependence of carrier injection across organic heterojunctions (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1063/1.3536530
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Journal titleJournal of Applied Physics
Article number23711
SubjectBarrier heights; Benzimidazoles; Carbazolyl; Carrier injection; Deep traps; Escape probability; Experimental studies; Heterojunction devices; Hopping frequency; Injection barriers; Injection currents; Injection model; Low temperatures; Organic heterojunctions; Organic materials; Temperature dependence; Triphenyl amines; Tris(8-hydroxyquinoline) aluminum; Electric field measurement; Electric fields; Temperature distribution; Heterojunctions
AbstractWe present a theoretical and experimental study of carrier injection across organic heterojunctions of various barrier heights (0.4-1.0 eV) over a wide range of temperatures. An injection model with proposed escape probability function wesc is formulated to include the total hopping frequencies at both sides of the heterojunction. The model predicts that the injection current at low temperature can be dramatically modified by an extremely small amount of deep trap states. More importantly, the temperature dependence of the injection current is found to decrease with increasing the barrier height. This suggests that extracting the barrier height from the J versus 1/T plot, as commonly employed in literature, is problematic. Experimentally, hole-only heterojunction devices with injection barrier from 0.4 to 1.0 eV were fabricated by using various organic materials. 4, 4′, 4″ -tris(N-3-methylphenyl-N- phenyl-amino) triphenylamine was chosen as the injecting layer. The accepting layer was N, N′ -diphenyl- N, N′ -bis(1-naphthyl)(1, 1′ -biphenyl)- 4, 4′ -diamine, tris(8-hydroxyquinoline) aluminum (Alq), 4, 4′, 4″ -tris(N-carbazolyl)-triphenylamine, or 2, 2′, 2″ -(1,3,5-phenylene) tris(1-phenyl-1H-benzimidazole). The measured electric field and temperature dependence of the injection currents of the heterojunction devices were in good agreement with the calculation results. © 2011 American Institute of Physics.
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AffiliationNational Research Council Canada (NRC-CNRC); NRC Institute for Microstructural Sciences (IMS-ISM)
Peer reviewedYes
NPARC number21271206
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Record identifier5a36b3b1-71c7-4882-85d7-7ba7e017220c
Record created2014-03-24
Record modified2016-05-09
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