Single-Layer Perovskite LED with Composite Thin Film

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Solution Overview

Problem

Existing perovskite light-emitting diodes (Pero-LEDs) suffer from low luminance intensity due to inefficient electron and hole injection, and high turn-on voltages, which are not effectively addressed by multilayer device structures.

Innovation Solution

A single-layer Pero-LED structure utilizing a composite thin film of cesium lead tribromide (CsPbBr3) combined with poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) as an ionic-conducting and insulating polymer, respectively, to enhance charge-carrier injection and form an in-situ p-i-n junction, reducing turn-on voltage and increasing luminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multilayer device structures are used to enhance electron and hole injection, then charge injection efficiency is improved, but device complexity increases and turn-on voltage becomes much higher than bandgap/e

Engineering Contradiction:

Improvecharge injection efficiencyVSAvoiddevice structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functional layers (hole injection layer, perovskite emissive layer, and electron injection layer) into a single integrated layer. This single layer simultaneously performs hole injection, charge transport, and light emission functions, eliminating the need for separate multilayer structures while maintaining efficient charge injection and reducing device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single layer in the invention serves multiple functions: it acts as a hole injection layer, a charge transport layer, and an emissive layer simultaneously. This multi-functional design replaces the specialized multilayer structure where each layer has a dedicated function, thereby simplifying device architecture while preserving injection efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multilayer device structures are used to enhance charge injection, then charge injection efficiency is improved, but turn-on voltage increases to more than 3.0 V

Engineering Contradiction:

Improvecharge injection efficiencyVSAvoidturn-on voltage

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

By merging the hole injection, charge transport, and emission functions into one layer, the patent eliminates the voltage drops that occur across multiple interfaces in multilayer structures. This results in a lower turn-on voltage that remains close to the bandgap/e value, reducing energy consumption while maintaining efficient charge injection.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional Pero-LED structures are used, then device fabrication is simplified, but luminance intensity remains low at maximum 20,000 cd m−2

Engineering Contradiction:

Improvefabrication simplicityVSAvoidluminance intensity

Core Design Contradiction:

Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent employs a composite material system within the single layer, combining perovskite emissive materials with organic charge transport materials. This composite structure enables efficient charge injection and transport while achieving ultra-high luminance intensity of 593,178 cd m−2, dramatically improving upon conventional structures without complicating fabrication.

Inventive Principle:

Principle #40Composite materials

4Ease of manufacture

If discontinuous perovskite emissive layer is used, then fabrication is easier, but current leakage occurs preventing high luminance intensity

Engineering Contradiction:

Improvefabrication easeVSAvoidcurrent leakage control

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The composite single-layer structure creates a continuous, pinhole-free film that eliminates current leakage pathways. The integration of perovskite with organic materials forms a homogeneous composite that maintains structural integrity and electrical continuity, achieving both ease of fabrication and reliable current control for high luminance output.

Inventive Principle:

Principle #40Composite materials

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 achieves a maximum luminance of 593,178 cd m−2 at 4.9 V with a sub-bandgap turn-on voltage, significantly improving brightness by 30 times over previous MA-Pero LEDs and 150 times over Cs-Pero LEDs, and outperforming OLEDs and quantum-dot LEDs in terms of luminous efficiency.

Implementation Method 1

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

light-emitting diodes (LEDs)... single-layer LEDs utilizing a composite thin film of organometal halide perovskite polymer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11239429B1Superluminescent halide perovskite light-emitting diodes with a sub-bandgap turn-on voltage

Publication Date: 2022.02.01 FLORIDA STATE UNIV RES FOUND INC

AI summary

An emissive perovskite ternary composite thin film comprising a perovskite material, an ionic-conducting polymer and an ionic-insulating polymer is provided. Additionally, a single-layer LEDs is described using a composite thin film of organometal halide perovskite (Pero), an ionic-conducting polymer (ICP) and an ionic-insulating polymer (IIP). The LEDs with Pero-ICP-IIP composite thin films exhibit a low turn-on voltage of about 1.9V (defined at 1 cd m−2 luminance) and a luminance of about 600,000 cd m−2.