Quantum Efficiency Evolution In A Hole-injection Layer Inserted Within A Polymer Light-emitting Diode

Part1We first address the formation of the exciton. A PLED generally consists of three layers:a luminescent polymer layer embedded between two electrodes. When the conjugated polymer layer is in its ground state, the lattice configuration of the polymer is homogeneous dimerization, producing a gap between the highest-occupied molecular orbital (HOMO) and lowest-unoccupied molecular orbital (LUMO). In order to describe the properties of the conjugated polymer, the extended Su-Schreiffer-Heeger-Hubbard (SSHH) Hamiltonian provides a valid model to quantitatively describe this effect, where not only is the electron-phonon coupling considered, but also the electron-electron interaction is taken into account, and using the Brazovskii-Kirova symmetry-breaking theorem, and the Hartree-Fock approximation,we can describe the atomic movement of the lattice through classical dynamics by the equation:Part2we suggest induce triplet exciton to decay radiatively. Here, a hole-injection layer is inserted between the polymer layer and positive electrode of the PLED to introduce a positively charged carrier, such as a polaron, into the polymer. In order to break the limitation of25%for the quantum efficiency, when a positive polaron is injected through the inserted hole-injection layer, the neutral triplet exciton is assumed to reside in the middle of the polymer chain. Simultaneously, if an external electric field applied along the chain, the positive polaron is driven to approach the triplet exciton, leading to a collision between the polaron and exciton. The collision causes the triplet exciton to break the restriction of the Pauli repulsion for the triplet exciton as well as the electronic transition.that the collision between the triplet exciton and injected polaron immediately improves the quantum efficiency.