Light Extraction Film Design for Efficient OLED Devices
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Summary
Problems
Organic Light Emitting Diodes (OLEDs) suffer from low light extraction efficiency due to internal reflections at interfaces between high and low index layers, leading to significant light loss, and existing solutions are either ineffective or incompatible with existing fabrication processes.
Innovation solutions
A multifunctional optical film with a flexible substrate, a structured layer of nanostructures, and a backfill layer with a contrasting refractive index, positioned within the evanescent zone to disrupt total internal reflection and enhance light extraction, while also providing mechanical support, barrier protection, and electrical conductance.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If scattering or diffractive elements are introduced at the core-to-substrate interface to improve light extraction, then light extraction efficiency is improved, but fabrication complexity and device reliability deteriorate due to the difficulty of creating defect-free interfaces
Why choose this principle:
A separate light extraction film is introduced as an intermediary component between the OLED core and substrate. This film contains the scattering or diffractive elements (such as microlenses, prisms, or roughened surfaces) while maintaining a smooth interface with the OLED core. The intermediary film thus enables light extraction enhancement without compromising the reliability of the core device interface.
Principle concept:
If scattering or diffractive elements are introduced at the core-to-substrate interface to improve light extraction, then light extraction efficiency is improved, but fabrication complexity and device reliability deteriorate due to the difficulty of creating defect-free interfaces
Why choose this principle:
The light extraction function is segmented from the core OLED structure and placed in a separate film layer. This segmentation allows the light extraction elements to be optimized independently without affecting the fabrication and reliability of the core device, while still achieving the desired light extraction improvement.
Application Domain
Data Source
AI summary:
A multifunctional optical film with a flexible substrate, a structured layer of nanostructures, and a backfill layer with a contrasting refractive index, positioned within the evanescent zone to disrupt total internal reflection and enhance light extraction, while also providing mechanical support, barrier protection, and electrical conductance.
Abstract
A multifunctional optical film for enhancing light extraction includes a flexible substrate, a structured layer, and a backfill layer. The structured layer effectively uses microreplicated diffractive or scattering nanostructures located near enough to the light generation region to enable extraction of an evanescent wave from an organic light emitting diode (OLED) device. The backfill layer has a material having an index of refraction different from the index of refraction of the structured layer. The backfill layer also provides a planarizing layer over the structured layer in order to conform the light extraction film to a layer of an OLED lighting device such as solid state lighting devices or backlight units. The film may have additional layers added to or incorporated within it to an emissive surface in order to effect additional functionalities beyond improvement of light extraction efficiency.