Magnetoconductance response due to the triplet exciton–charge interaction in organic light-emitting diodes

• The MC effects observed in three OLEDs can all be separated into two independent components which can be fitted with two non-Lorentzian functions.
• The second MC component can be attributed to the triplet exciton-charge interactions according to its current and temperature dependences.
• The sign of MC effect induced by the triplet exciton-charge interactions can be either positive or negative due to the different reaction channel.

The magnetoconductance (MC) effects in three organic light-emitting diodes have been measured over a range of operating current and temperatures. The peculiar roles played by the hyperfine field and triplet excitons are outlined by fitting the MC traces using the sum of two non-Lorentzian functions. The MC response evident at large magnetic fields is confirmed to be resulted from the triplet exciton–charge interaction by investigating its variation with the triplet population. The remarkable agreement between the experimental data and fit lines demonstrates that the method used in this work could help to identify the correct models for understanding the fundamental mechanism behind the magnetic field effects universally observed in organic devices.

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