Soluble Dithiophene Polymers for Organic Photovoltaics
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Solution Overview
Problem
Current covalent organic polymers derived from benzo[1,2-b:4,5-b′]dithiophene are insoluble, limiting their application in devices, and there is a need for novel compounds with enhanced solubility for organic photovoltaics and other applications like capacitors and solar cells.
Innovation Solution
A novel compound of formula (I), (4,8-bis(5-(trimethylstannyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane), and its corresponding polymer (II), are synthesized using improved processes, including a one-pot gram-scale synthesis, to achieve high yields and solubility, enabling their use in device fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If covalent organic polymers are synthesized from benzo[1,2-b:4,5-b′]dithiophene, then electron donor capabilities are enhanced, but solubility is lost
Solution Approach 1:
The patent applies local quality by introducing specific solubilizing groups (alkyl chains, alkoxy groups, sultone groups) at particular positions of the polymer structure while maintaining the core electron-donating benzo[1,2-b:4,5-b′]dithiophene units. This allows different parts of the molecule to have different functions: the core provides electron donor capability while the peripheral groups provide solubility.
Solution Approach 2:
The patent creates composite polymer structures by combining benzo[1,2-b:4,5-b′]dithiophene units with various functional groups including alkyl chains, alkoxy groups, and sultone groups. These composite structures achieve both high electron donor capability and improved solubility through the synergistic combination of different molecular components.
2Productivity
If conventional synthesis methods are used for DTBDT, then reaction proceeds, but yield is low
Solution Approach 1:
The patent applies parameter changes by optimizing reaction conditions including using specific catalysts (Pd(PPh3)4, Pd(dppf)Cl2), controlling reaction temperature (80-110°C), adjusting solvent systems (toluene, dichloromethane, chloroform), and using appropriate equivalents of reagents. These parameter optimizations collectively achieve synthesis yields of 85-95% for DTBDT.
Solution Approach 2:
The patent uses palladium catalysts as intermediaries to facilitate the cross-coupling reaction between 2,6-dibromobenzo[1,2-b:4,5-b′]dithiophene and thiophene derivatives. The catalyst acts as a mediator that enables the reaction to proceed efficiently with high yields by lowering the activation energy and providing an alternative reaction pathway.
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 synthesis provides high-yield, soluble polymers suitable for organic photovoltaics and other applications, with improved electrochemical and optical properties, facilitating the construction of efficient devices for solar and capacitor applications.
Implementation Method 1
a) Adding a solution of 2-bromothiophene in solvent to a suspension of magnesium and iodine in solvent at 0° C. followed by refluxing for the period in the range of 1 to 2 hr; b) Adding 4,8-dehydrobenzo [1,2-b:4,5-b′] dithiophene-4,8-dione to the reaction mixture of step (a) followed by stirring reaction mixture at a temperature in the range of 50 to 60° C. for the period in the range of 5 to 7 hours
Implementation Method 2
b) Degassing the solution of step (a) and adding Pd(PPh3)4 followed by heating the reaction mixture at a temperature in the range of 100 to 110° C. for the period in the range of 70 to 74 hrs
Data Source
AI summary
The present invention disclosed a novel (4,8-bis(5-(trimethylstannyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)bis(trimethylstannane) compound, its preparation and use for the synthesis of polymers, which is used to build devices for capacitor and solar applications. The present invention further discloses to an improved process for the synthesis of DTBDT having improved yields.