Charge Transporting Liquid Crystal Photoalignment Layer
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Solution Overview
Problem
Commercially available photoalignment layers used in OLEDs are insulating, preventing current flow and requiring higher operating voltages, and hole injection layers like PEDT/PSS can corrode indium-tin oxide anodes and have poor adhesion, leading to poor device performance and shortened lifetimes.
Innovation Solution
Development of surface derivatising materials with combined charge transporting and liquid crystal photoalignment properties, comprising charge-transporting and photoalignment moieties connected through covalent bonds, and a method for forming these layers by immersing substrates in solvent solutions followed by drying, which allows for improved hole conduction and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoalignment layer is used to achieve uniform liquid crystal alignment, then alignment quality improves, but operating voltage increases due to poor conductivity
Solution Approach 1:
By merging photoalignment and charge transport functions into a single doped layer, the patent simultaneously achieves uniform liquid crystal alignment and sufficient electrical conductivity. The aligned liquid crystals enable precise optical control while the charge transporting dopant ensures low-resistance current flow, thereby maintaining alignment quality without the penalty of elevated operating voltages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables efficient current flow and uniform liquid crystal alignment, reducing operating voltage and enhancing device performance and lifespan by forming charge transporting liquid crystal photoalignment layers that support higher hole currents and maintain alignment properties.
Implementation Method 1
when exposed to intense, polarised UV light, undergo a photochemical reaction that imparts to them a surface energy anisotropy
Implementation Method 2
hole injection layer 120, then through the photoalignment layer 130 so as pass into the emitter layer 140 energising it
Implementation Method 3
liquid crystals coated on to the surface of such a previously exposed material preferentially wet that surface with their molecular long axes aligned in a preferred direction
Data Source
AI summary
A charge transporting, liquid crystal photoalignment material comprising a charge transporting moiety connected through covalent chemical bonds to a surface derivatising moiety, and a photoalignment moiety connected through covalent chemical bonds to a surface derivatising moiety.