Non-Stoichiometric NiOx Nanoparticles for Flexible Optoelectronics

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The fabrication of highly efficient nickel oxide (NiOx) hole transport layers (HTLs) for optoelectronic devices via low-temperature solution processes is challenging due to the need for thermal annealing and oxygen-plasma treatment, which are not compatible with flexible devices and result in instability and degradation.

Innovation Solution

A chemical precipitation and combustion method is used to synthesize non-stoichiometric NiOx nanoparticles, allowing for the formation of NiOx HTL films at room temperature without post-treatments, enabling stable and efficient hole transport in optoelectronic devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If thermal annealing and oxygen-plasma treatment are used to fabricate NiOx HTLs, then electrical conductivity and hole transport efficiency are improved, but device stability deteriorates and compatibility with flexible substrates is lost

Engineering Contradiction:

Improvehole transport efficiencyVSAvoiddevice stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameters of NiOx by controlling oxygen content to create non-stoichiometric NiOx with optimized electrical properties. This allows achieving high hole transport efficiency without requiring thermal annealing, thereby maintaining device stability and flexibility compatibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive and complex post-treatment processes (thermal annealing, oxygen-plasma treatment) with a simple low-temperature solution processing method. This eliminates the need for expensive equipment and complex process steps while achieving comparable or superior device performance

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If thermal annealing processes are used to fabricate NiOx HTLs, then material crystallinity and electrical properties are improved, but compatibility with flexible substrates deteriorates

Engineering Contradiction:

Improvematerial crystallinityVSAvoidflexible substrate compatibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the processing temperature parameter from high-temperature thermal annealing to low-temperature solution processing. This allows achieving sufficient material crystallinity and electrical properties without exposing flexible substrates to damaging high temperatures, thereby maintaining substrate integrity and device flexibility

Inventive Principle:

Principle #35Parameter changes

3Reliability

If conventional thermal processing methods are used to fabricate NiOx HTLs, then electrical conductivity is improved, but production cost and energy consumption increase

Engineering Contradiction:

Improveelectrical conductivityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the processing temperature parameter from high-temperature thermal annealing to low-temperature solution processing. This dramatically reduces energy consumption while achieving comparable or superior electrical conductivity through optimized non-stoichiometric NiOx composition and simple drying processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces thermal energy-based processing (thermal annealing, plasma treatment) with chemical solution-based processing. This substitution uses chemical reactions and solution chemistry to achieve material modification without requiring large amounts of thermal energy, thereby reducing energy consumption and production costs

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 NiOx HTL films demonstrate superior optical, electrical, and surface properties, achieving high power conversion efficiency in organic solar cells and competitive performance with PEDOT:PSS-based devices, while being compatible with flexible substrates and reducing production costs and energy consumption.

Implementation Method 1

The present invention is directed to a chemical precipitation method for synthesizing NiOx nanoparticles

Methodology Applied

Scientific EffectChemical precipitation: Precipitation

Implementation Method 2

The combustion in air promotes oxygen interactions with a nickel-deficient lattice, further forming different valence-state compositions, including NiO (Ni2+), NiOOH (Ni3+), and Ni2O3 (Ni3+)

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS10604419B2Simple approach for preparing post-treatment-free solution processed non-stoichiometric NiO<sub>x </sub>nanoparticles as conductive hole transport materials

Publication Date: 2020.03.31 THE UNIVERSITY OF HONG KONG

AI summary

High-quality noN-stoichiometric NiOx nanoparticles are synthesized by a facile chemical precipitation method. The NiOx film can function as an effective p-type semiconductor or hole transport layer (HTL) without any post-treatments, while offering wide temperature applicability from room-temperature to 150° C. For demonstrating the potential applications, high efficiency is achieved in organic solar cells using NiOx HTL. Better performance in NiOx based organic light emitting diodes is obtained as compared to devices using PEDOT:PSS. The solution-processed NiOx semiconductors at room temperature can favor a wide-range of applications of large-area and flexible optoelectronics.