Conjugated Polymers Difluoralkyl Side Chains Solubility

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Solution Overview

Problem

Conjugated polymers used in organic photovoltaic devices face limitations such as limited solubility in organic solvents, low power conversion efficiency, and difficulties in synthesis suitable for mass production, which hinder their application in large-scale production and device performance.

Innovation Solution

Development of conjugated polymers incorporating 4,8-bis(1,1-difluoralkyl)-benzo[1,2-b:4,5-b']dithiophene units, which enhance solubility, charge carrier mobility, and oxidative stability, and reduce bandgap, enabling improved light harvesting and device efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional conjugated polymers are used in organic photovoltaic devices, then device manufacturing by solution processing is enabled, but the polymers suffer from limited solubility in organic solvents which inhibits suitability for device manufacturing

Engineering Contradiction:

Improvesuitability for solution processingVSAvoidsolubility in organic solvents

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by modifying the chemical structure of the polymer through the introduction of difluoralkyl side chains at the 4,8-positions of the benzo[1,2-b:4,5-b']dithiophene core. This structural modification changes the solubility parameters of the polymer, enabling it to dissolve in common organic solvents while maintaining its semiconducting properties and low bandgap characteristics.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If conjugated polymers with narrow bandgap are designed to absorb maximum solar spectrum, then light harvesting is improved, but the polymers show only limited power conversion efficiency in OPV bulk-hetero-junction devices

Engineering Contradiction:

Improvelight harvesting efficiencyVSAvoidpower conversion efficiency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs composite material design by creating a copolymer structure that combines electron-rich donor units (benzo[1,2-b:4,5-b']dithiophene with difluoralkyl side chains) and electron-deficient acceptor units. This donor-acceptor architecture creates a narrow bandgap composite material that simultaneously achieves improved light harvesting and enhanced power conversion efficiency through optimized charge separation and transport properties.

Inventive Principle:

Principle #40Composite materials

3Reliability

If conjugated polymers are synthesized to achieve good electronic properties, then charge carrier mobility is improved, but the polymers are difficult to synthesize and require methods unsuitable for mass production

Engineering Contradiction:

Improvecharge carrier mobilityVSAvoidsynthesis suitability for mass production

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies segmentation by designing the polymer as a copolymer with distinct donor and acceptor units that can be synthesized separately and then coupled through well-established polymerization reactions. The difluoralkyl side chains are introduced as modular substituents on the core structure, allowing for systematic synthesis and purification that is compatible with scalable manufacturing processes while maintaining high charge carrier mobility.

Inventive Principle:

Principle #1Segmentation

4Ease of operation

If conjugated polymers are designed for high solubility to enable solution processing, then processibility is improved, but the polymers show only limited charge carrier mobility

Engineering Contradiction:

ImproveprocessibilityVSAvoidcharge carrier mobility

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies local quality by introducing difluoralkyl side chains specifically at the 4,8-positions of the benzo[1,2-b:4,5-b']dithiophene core, while keeping the conjugated backbone structure intact. This localized modification improves solubility and processibility without disrupting the electronic properties and charge carrier mobility that depend on the conjugated backbone. The side chains provide steric bulk and solubility enhancement locally, while the core maintains its electronic function.

Inventive Principle:

Principle #3Local quality

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 polymers exhibit high solubility, charge carrier mobility, and stability, leading to enhanced power conversion efficiency and suitability for large-scale production in organic photovoltaic devices.

Implementation Method 1

the conjugated polymer serves as the main absorber of the solar energy

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

exhibit good electronic properties, especially a high charge carrier mobility

Methodology Applied

Scientific EffectCharge carrier mobility: Conduction (electrical)

Data Source

PatentEP2700111B1Conjugated polymers

Publication Date: 2015.01.21 MERCK PATENT GMBH

Figure 1

AI summary

The invention relates to novel polymers containing one or more repeating units based on 4,8-bis(1,1-difluoralkyl)-benzo[1,2-b:4,5-b']dithiophene or derivatives thereof, methods for their preparation and monomers used therein, blends, mixtures and formulations containing them, the use of the polymers, blends, mixtures and formulations as semiconductor in organic electronic (OE) devices, especially in organic photovoltaic (OPV) devices, and to OE and OPV devices comprising these polymers, blends, mixtures or formulations.