Three-dimensional pixel configurations for optical outcoupling of OLED displays-optical simulation

Because of considerations on image quality and fabrication/integration compatibility, current active-matrix OLED displays (AMOLEDs) hardly adopt any effective light outcoupling techniques/structures, and it remains an unsolved critical technical issue. Recently, through optical simulation, we proposed a three-dimensional (3D) pixel configuration as a potential and promising way to boost light outcoupling of OLED display pixels. By extending the bottom reflective electrode to bank slope of the pixel definition layer (PDL) and selectively filling the bank opening (concave area) with high-index filler to form the optically reflective concave structure, it is possible to give several-fold light extraction enhancement. In this paper, we further extend the simulation work by evaluating effects of more realistic graded bank slopes vs straight bank slope, less challenging nonpatterned (blanket) high-index filler vs patterned filler, and real OLED layer stacks and properties. The optical simulation clearly reveals that light extraction enhancement can be mostly kept with more realistic graded bank profiles and even less ideal (but also less challenging) nonpatterned filler can provide substantial extraction enhancement. The graded bank structure also provides beneficial effects on viewing characteristics.