Halogenated Thiophene End Groups for A-D-A Acceptors
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Solution Overview
Problem
Current acceptor-donor-acceptor (A-D-A) small molecular acceptors (SMAs) with unsubstituted thiophene end groups exhibit inferior performance in organic solar cells due to weak intramolecular charge transfer and blue-shifted absorption, leading to lower short-circuit current density and fill factor.
Innovation Solution
Substituting thiophene end groups with halogenated atoms or alkyl groups enhances electron-withdrawing ability, extending absorption range and promoting molecular packing, thereby improving electron transport and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If unsubstituted thiophene end groups are used in A-D-A acceptors, then electron-rich character enhances, but intramolecular charge transfer weakens causing blue-shifted absorption and reduced JSC
Solution Approach 1:
The patent applies local quality by introducing different substituents (electron-withdrawing groups like halogens or electron-donating groups like alkyl chains) at specific positions of the thiophene end groups. This allows different regions of the molecule to have different electronic properties, balancing the electron-rich character with enhanced charge transfer capability, thereby resolving the contradiction between electron richness and productivity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the substituent types and positions on the thiophene end groups. By changing these molecular parameters, the patent optimizes both the electron-rich character and the intramolecular charge transfer efficiency, achieving improved JSC while maintaining the beneficial electronic properties of thiophene end groups.
2Shape
If unsubstituted thiophene end groups are used in A-D-A acceptors, then molecular packing relies on π-π stacking, but electron transport remains limited due to weak charge transfer
Solution Approach 1:
The patent applies local quality by introducing different substituents (electron-withdrawing groups like halogens or electron-donating groups like alkyl chains) at specific positions of the thiophene end groups. This allows different regions of the molecule to have different electronic properties, balancing the electron-rich character with enhanced charge transfer capability, thereby resolving the contradiction between electron richness and productivity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the substituent types and positions on the thiophene end groups. By changing these molecular parameters, the patent optimizes both the electron-rich character and the intramolecular charge transfer efficiency, achieving improved JSC while maintaining the beneficial electronic properties of thiophene end groups.
3Productivity
If halogenated substituents are introduced to enhance electron-withdrawing ability and absorption, then device performance improves, but molecular complexity increases
Solution Approach 1:
The patent applies local quality by introducing different substituents (electron-withdrawing groups like halogens or electron-donating groups like alkyl chains) at specific positions of the thiophene end groups. This allows different regions of the molecule to have different electronic properties, balancing the electron-rich character with enhanced charge transfer capability, thereby resolving the contradiction between electron richness and productivity.
Solution Approach 2:
The patent employs parameter changes by systematically varying the substituent types and positions on the thiophene end groups. By changing these molecular parameters, the patent optimizes both the electron-rich character and the intramolecular charge transfer efficiency, achieving improved JSC while maintaining the beneficial electronic properties of thiophene end groups.
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 resulting A-D-A acceptors demonstrate red-shifted absorption, stronger molecular packing, and higher power conversion efficiency, achieving up to 12.7% PCE with enhanced VOC, JSC, and FF, outperforming unsubstituted thiophene end group-based devices.
Implementation Method 1
the halogen atoms endow the thiophene-based end groups with stronger electron-withdrawing ability relative to their non-halogenated counterparts due to the strong electronegativity, which extends the absorption range and enhances extinction coefficients
Implementation Method 2
halogenated molecules have been shown to facilitate molecular packing induced by noncovalent interactions, which further promotes efficient electron transport
Implementation Method 3
the molecular packing of A-D-A SMAs largely relies on the π-π stacking of the end groups, meaning that closely stacked end groups facilitate electron transport
Implementation Method 4
the more electron-rich thiophene rings weaken the intramolecular charge transfer (ICT) effect between the core and the end groups, which causes a blue-shifted absorption and a decreased extinction coefficient of the acceptor
Data Source
AI summary
Provided herein are small molecular acceptor compounds containing thiophene end groups, methods for their preparation and intermediates used therein, the use of formulations containing the same as semiconductors in organic electronic devices, especially in organic photovoltaic and organic field-effect transistor devices, and to organic electronic and organic photovoltaic devices made from these formulations.