Branching Alkyl Chains Enhance Carrier Mobility in Organic Semiconductors
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Solution Overview
Problem
Current polymer field effect transistor materials and solar cell materials face challenges with low mobility, which hinders the performance of organic electronics such as organic solar cells and field effect transistors.
Innovation Solution
The development of novel branching alkyl chains that serve as solubilizing groups in organic conjugated polymers, reducing π-π stacking effects and increasing carrier mobility, while ensuring solubility, for use in organic solar cells, light emitting diodes, and field effect transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional linear alkyl chains are used as solubilizing groups in organic conjugated polymers, then solubility is improved, but carrier mobility remains low due to strong π-π stacking effects
Solution Approach 1:
The patent divides the continuous linear alkyl chain into segmented branching structures (e.g., 2-ethylhexyl, 2-propylheptyl groups) attached at specific positions on the conjugated backbone. This segmentation creates spatial separation between adjacent polymer chains, reducing π-π stacking interactions while maintaining solubility through the branched alkyl segments.
Solution Approach 2:
The invention transitions from one-dimensional linear alkyl chains to three-dimensional branching structures. The branched alkyl groups extend in multiple directions perpendicular to the conjugated backbone, creating steric hindrance that prevents close packing of polymer chains and reduces π-π stacking in the vertical dimension while maintaining horizontal conjugation.
2Reliability
If strong π-π stacking is promoted to increase carrier mobility, then mobility is improved, but solubility deteriorates
Solution Approach 1:
The patent applies different structural qualities to different parts of the polymer: the conjugated backbone maintains planarity and electronic conjugation for charge transport, while the attached branching alkyl groups provide local steric bulk for solubility. This local differentiation allows simultaneous optimization of both mobility and solubility in different regions of the molecule.
3Ease of operation
If linear alkyl chains are used for solubilization, then processing ease is improved, but device performance is limited by low mobility
Solution Approach 1:
The patent creates a composite molecular structure combining the conjugated backbone (for electronic function) with branching alkyl side chains (for processing function). This molecular-level composite structure integrates both solubility and high mobility characteristics, enabling solution processing of high-performance materials.
Data Source
Figure 1(a)~2
AI summary
The invention discloses a compound having branching alkyl chains, the method for preparing the same and use thereof in photoelectric devices. By applying the branching alkyl chains as the solubilizing group to the preparation of organic conjugated molecules (for example, organic conjugated polymers), the number of methylenes between the resultant alky side chains and the backbone, i.e., m>1, which can effectively reduce the effect of the alkyl chains on the backbone π-π stacking, thereby ensuring the solubility of the organic conjugated molecule while greatly increasing the mobility of their carriers. It is suitable for an organic semiconductor material in photoelectric devices such as organic solar cells, organic light emitting diodes and organic field effect transistors, etc.