Symmetric Non-Fullerene Acceptors for Thermal and Solution Processing

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Solution Overview

Problem

Current non-fullerene acceptor materials for organic photovoltaic cells sublime and can only be solution processed, limiting their stability and application in devices.

Innovation Solution

Development of symmetrical non-fullerene acceptor compounds with specific molecular structures that minimize orbital overlap and have a small energy difference between S1 and T1 CT states, eliminating ground state dipole moments, and allowing for both thermal and solution processing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If non-fullerene acceptor materials are used to improve power conversion efficiency, then PCE is improved, but the materials sublime and can only be solution processed, limiting stability

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidstability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent changes the molecular structure parameters of non-fullerene acceptors by introducing symmetrical D-A-D architecture with specific electron-donating groups (carbazole, triphen胺) and electron-accepting groups (cyanoacrylate, malononitrile). This structural parameter change eliminates ground state dipole moments and minimizes orbital overlap, thereby improving thermal stability while maintaining charge transfer capabilities and power conversion efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite molecular structures by combining multiple functional groups (electron-donating carbazole/triphen胺 groups, electron-accepting cyanoacrylate/malononitrile groups, and linking groups) into symmetrical D-A-D architectures. These composite structures exhibit both high power conversion efficiency and improved thermal stability, resolving the contradiction between efficiency and stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If non-fullerene acceptor materials with extended π-systems are used to enhance charge transfer, then charge transfer capability is improved, but the materials become suitable only for solution processing, limiting manufacturing options

Engineering Contradiction:

Improvecharge transfer capabilityVSAvoidprocessing method versatility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent optimizes the π-system extension parameter by carefully selecting linking groups (phenylene, pyridine, triazine) that provide adequate electronic coupling without excessive extension. This parameter optimization enables the materials to maintain charge transfer capability while achieving sufficient thermal stability for vacuum deposition processing, thereby expanding processing method versatility

Inventive Principle:

Principle #35Parameter changes

3Reliability

If symmetrical D-A-D structures are designed to eliminate ground state dipole moments, then charge trapping is reduced, but molecular structure complexity increases

Engineering Contradiction:

Improvecharge trapping tendencyVSAvoidmolecular structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies asymmetry in a controlled manner by using symmetrical D-A-D architectures where identical electron-donating groups are positioned symmetrically around a central electron-accepting core. This deliberate symmetrical arrangement eliminates ground state dipole moments and reduces charge trapping, while the modular design keeps structural complexity manageable through systematic group repetition

Inventive Principle:

Principle #4Asymmetry

4Reliability

If thermal processing is enabled for improved stability, then material stability is improved, but processing temperature control becomes more critical

Engineering Contradiction:

Improvematerial stabilityVSAvoidprocessing temperature control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the thermal stability parameter by introducing symmetrical D-A-D structures with robust covalent bonding between electron-donating and electron-accepting groups. This structural modification raises the thermal decomposition temperature and improves material stability during processing, while the enhanced thermal stability provides a broader processing window that actually reduces temperature control sensitivity

Inventive Principle:

Principle #35Parameter changes

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 new compounds enhance the stability and efficiency of organic photovoltaic cells by maintaining charge transfer capabilities while enabling both thermal and solution processing, improving power conversion efficiency.

Implementation Method 1

formation of a charge transfer excited state on optical excitation

Methodology Applied

Scientific EffectCharge transfer: Photoelectric Effect

Implementation Method 2

intense red/NIR absorbance

Methodology Applied

Scientific EffectAbsorption: Absorption (EM radiation)

Data Source

PatentUS20250270444A1Symmetric Charge Transfer Compounds for Organic Photovoltaics

Publication Date: 2025.08.28 UNIV OF SOUTHERN CALIFORNIA

AI summary

The present disclosure is related to organic acceptor-donor-acceptor compounds as non-fullerene acceptors for use in organic photovoltaics.