Phosphorescent Polymer for OLED White Light Emission

The patent divides the light-emitting layer into multiple segments, each containing different phosphorescent dopants (e.g., iridium complexes for green emission, platinum complexes for red emission) embedded in separate host polymer matrices. This segmentation allows each segment to be optimized for its specific emission wavelength and stability requirements, preventing the degradation issues that would affect the entire device if a single material system were used.

The patent employs composite material structures where phosphorescent dopant complexes are embedded within polymeric host materials. Specifically, it uses combinations such as iridium complexes with cyclometalating ligands in polyfluorene hosts, and platinum complexes with carbene ligands in polystyrene hosts. These composite structures provide both the phosphorescent emission properties needed for color rendering and the structural stability required for extended device lifetime.

The patent optimizes the concentration parameters of phosphorescent dopants within specific ranges (e.g., 0.1-5 wt% for iridium complexes, 0.5-10 wt% for platinum complexes) to achieve maximum emission efficiency while minimizing material consumption. It also adjusts the host-guest ratio parameters to ensure efficient energy transfer from host to dopant without requiring excessive amounts of expensive metal complexes.

The patent replaces some expensive, scarce metal complexes (such as iridium and platinum) with more abundant and cost-effective alternative phosphorescent materials including organic phosphors and earth-abundant metal complexes (such as copper or aluminum complexes). This substitution maintains acceptable emission efficiency while dramatically reducing device cost and material scarcity concerns.