Perovskite LED Nano-Grating Light Extraction
Solution Overview
Problem
Perovskite light-emitting diodes suffer from inefficient light extraction due to Lambertian radiation mode, leading to photon loss in the waveguide mode, and lack control over light directionality, which limits their application in fields like biosensors and visible light communication.
Innovation Solution
Incorporating a periodic nano-grating structure into the electron transport layer of the perovskite light-emitting diode, which can be dielectric or metallic, to control the directionality and enhance light extraction efficiency by converting waveguide mode light into substrate mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar perovskite light-emitting diode structure is used, then the device structure is simple, but the light extraction efficiency is low due to Lambertian radiation mode and waveguide mode photon loss
Solution Approach 1:
The patent introduces a periodic nano-grating structure into the electron transport layer, transforming the planar two-dimensional structure into a three-dimensional structured design. This dimensional change creates additional light extraction pathways by coupling waveguide mode photons into substrate mode through the grating's periodic modulation, thereby improving light extraction efficiency without fundamentally complicating the device architecture
Solution Approach 2:
The patent modifies the electron transport layer by introducing a periodic nano-grating structure with specific geometric parameters (period, depth, duty cycle). This parameter change alters the optical properties of the layer, enabling it to function as both an electron transport medium and a light extraction enhancement structure, thus improving light extraction efficiency while maintaining structural integration
2Ease of manufacture
If a planar perovskite light-emitting diode structure is used, then the device structure is simple, but the directionality of emitted light cannot be controlled
Solution Approach 1:
By introducing the periodic nano-grating structure, the patent adds a new dimensional element to the planar device. This grating structure imposes a preferred orientation on the emitted light, transforming the omnidirectional Lambertian radiation into a more directional emission pattern. The grating's periodic structure creates momentum matching conditions that favor specific emission angles, thereby providing directionality control while maintaining the overall simplicity of the device structure
Solution Approach 2:
The periodic nano-grating structure introduces asymmetry into the otherwise symmetric planar device structure. This asymmetry breaks the rotational symmetry of the Lambertian radiation pattern, creating a preferred emission direction. The grating's periodic modulation of the optical path length and refractive index creates directional bias in light extraction, enabling control over light directionality
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 nano-grating structure effectively increases light extraction efficiency and allows continuous adjustment of emitted light angles, significantly enhancing the performance of perovskite light-emitting diodes.
Implementation Method 1
the nano-grating structure, which can effectively damage the waveguide mode of the light when traveling through the device, and couple the waveguide mode into the substrate mode to increase the efficiency of light extraction
Data Source
AI summary
This disclosure provides a perovskite light-emitting diode with an adjustable light field, including a glass layer, an anode, a hole transport layer, an emission layer, an electron transport layer and a cathode in sequence from top to bottom. The electron transport layer is provided with a periodic nano-grating structure.