Push-Pull Polymer for Organic Solar Cell Efficiency
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Solution Overview
Problem
Current organic solar cells using conjugated polymers suffer from low power conversion efficiency due to low sunlight absorption, difficulty in separating excitons into electrons and holes, and low carrier mobility, which limits their practical application compared to inorganic solar cells.
Innovation Solution
A novel polymer with electron donating and accepting groups is developed, which is used to create a photoactive layer in organic thin-film solar cells, enhancing hole mobility and power conversion efficiency through improved intermolecular packing and charge transfer characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional conjugated polymers are used in organic solar cells, then the device can be fabricated at low cost by solution processing, but the power conversion efficiency remains low due to poor sunlight absorption and low carrier mobility
Solution Approach 1:
The patent modifies the chemical structure of conjugated polymers by incorporating electron-donating groups (such as carbazole, triphen胺) and electron-accepting groups (such as benzothiadiazole, quinoxaline) to create push-pull structures. This changes the electronic parameters of the polymer, resulting in reduced bandgap, improved sunlight absorption across broader wavelengths, and enhanced charge carrier mobility while maintaining solution processability
Solution Approach 2:
The patent creates composite polymer structures by combining electron-donating and electron-accepting moieties within the same polymer chain or through blending different polymers. This composite approach at the molecular level enables simultaneous optimization of light absorption and charge transport properties, achieving power conversion efficiency comparable to inorganic semiconductors while retaining the advantages of organic materials
2Device complexity
If conventional conjugated polymers are used, then the device structure can be simplified, but exciton separation into electrons and holes is difficult due to high binding energy
Solution Approach 1:
The patent introduces local electron-donating and electron-accepting groups at specific positions within the polymer structure to create localized dipole moments and internal electric fields. This local modification enables efficient exciton separation at specific sites along the polymer chain without requiring complex device architectures, maintaining simple device structure while improving separation efficiency
3Temperature
If conventional conjugated polymers are used, then the material can be processed by low temperature solution processing, but carrier mobility is low due to trap formation and scattering between amorphous areas and chains
Solution Approach 1:
The patent incorporates structural features in the polymer design that pre-establish favorable packing arrangements and reduce trap sites before device fabrication. The electron-donating and electron-accepting groups are positioned to promote ordered molecular packing and reduce amorphous regions, thereby improving carrier mobility while maintaining low-temperature solution processing capability
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 novel polymer achieves high power conversion efficiency and improved carrier mobility, surpassing previous efficiencies of organic solar cells and approaching those of inorganic materials, making it suitable for practical application.
Implementation Method 1
Low band gap organic materials undergo intramolecular charge transfer (ICT) from electron-rich monomers to electron-deficient monomers. This phenomenon leads to a reduction in band gap, resulting in efficient absorption of sunlight over a broad range of wavelengths.
Implementation Method 2
Solar cells have received attention as inexhaustible, renewable, and environmentally friendly electrical energy sources.
Data Source
AI summary
The present invention relates to a novel polymeric material for a highly efficient organic thin-film solar cell with high hole mobility and power conversion efficiency. In the polymeric material, a compound containing an electron donating group represented by Formula 1 or 2 and a compound containing an electron accepting group represented by one of Formulae 3 to 8 are repeatedly introduced in an alternating manner.