Forbidden singlet exciton transitions induced by localization in polymer light-emitting diodes in a strong electric field

Electronic Two-Transition-Induced Enhancement of Emission Efficiency in Polymer Light-Emitting Diodes

With the development of experimental techniques, effective injection and transportation of electrons is proven as a way to obtain polymer light-emitting diodes (PLEDs) with high quantum efficiency. This paper reveals a valid mechanism for the enhancement of quantum efficiency in PLEDs. When an external electric field is applied, the interaction between a negative polaron and triplet exciton leads to an electronic two-transition process, which induces the exciton to emit light and thus improve the emission efficiency of PLEDs.

Fluorescence dynamics and dipole moment evolution of singlet exciton decay in conjugated polymers

Both fluorescence dynamics and time-dependent electron transitions are introduced within a previously developed molecule dynamics approach for treating conjugated polymers. This is able to provide a panoramic view of luminescence dynamics during singlet exciton decay, in which the fluorescence dynamics is largely determined by the electron population and the evolution of the dipole moment. The fluorescence intensity is weakened due to a reduced dipole moment and diminished decay rate of the electron, which validates a previous assumption based on experimental studies. The lifetime of the singlet exciton in a conjugated polymer is found to be 1.2 ns, and the calculated time profile of the fluorescence intensity is in agreement with recent experimental results.