Black Soluble Conjugated Polymers for High Mobility Solar Cells
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Solution Overview
Problem
Donor-acceptor π-conjugated polymers exhibit low power conversion efficiencies in photovoltaic cells due to limited light absorption across the visible spectrum and low charge carrier mobility, which hinders the development of high-performance flexible light-harvesting technologies like solar cells.
Innovation Solution
The development of soluble fused donor-acceptor conjugated polymers with isolated acceptor units and fused donor units that facilitate π-stacking and extended conjugation, allowing for strong light absorption throughout the visible spectrum and high charge carrier mobilities, enabling the creation of black-colored solar cells with improved energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If donor-acceptor π-conjugated polymers are used for photovoltaic cells, then the devices can be processed via low-cost solution methods, but the power conversion efficiency is limited due to low charge carrier mobility
Solution Approach 1:
The patent modifies the molecular structure parameters of the polymer by incorporating fused donor units (such as dibenzothiophene, dibenzoselenophene) and isolated acceptor units (such as benzothiadiazole, quinoxaline) to optimize the balance between solution processability and charge carrier mobility. This structural parameter change enables both low-cost processing and high performance
Solution Approach 2:
The patent creates composite molecular structures by combining electron-rich fused donor units with electron-poor acceptor units in a donor-acceptor configuration. This composite approach at the molecular level achieves synergistic effects that simultaneously improve light absorption, charge generation, and charge transport while maintaining solution processability
2Use of energy by moving object
If DA polymers are designed for broad visible spectrum absorption, then light harvesting capability is improved, but charge carrier mobility decreases due to poor π-stacking and large lamellar spacing
Solution Approach 1:
The patent optimizes structural parameters by using fused donor units with specific geometries (dibenzothiophene, dibenzoselenophene) that promote planarity and π-stacking, while controlling the spacing and positioning of acceptor units. This parameter optimization achieves both broad light absorption and high charge carrier mobility through improved molecular packing
Solution Approach 2:
The patent applies local quality by isolating acceptor units between fused donor units, creating distinct regions with different electronic properties. The fused donor units provide pathways for charge transport through their extended π-systems, while the isolated acceptor units serve as charge generation sites, optimizing both light harvesting and charge mobility locally
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
These polymers achieve strong absorbance across the entire visible spectrum and high charge carrier mobilities, enhancing the efficiency of solar energy harvesting and enabling the production of flexible, high-performance solar cells with superior light-harvesting capabilities.
Implementation Method 1
The fDA-CP absorbs light throughout the visible spectrum appearing black to the human eye
Implementation Method 2
π-stacking of adjacent polymer chains occurs with solid state interlamella separation of less than 4.5 Å
Implementation Method 3
photo-generated excitons or geminate electron-hole pairs must undergo diffusion and dissociation processes within the active layer of the device and a rapid transport of the dissociated charges to collection electrodes
Data Source
AI summary
A soluble fused donor-acceptor conjugated polymer (fDA-CP) is prepared that absorbs light throughout nearly all the visible spectrum and is essentially black to the human eye when in the neutral state. The conjugated polymer has acceptor units that are isolated by a plurality of fused donor units. The fDA-CP assumes a conformation that results in a close π-stacking between adjacent lamella with a separation of less than 4.5 Å in the solid state and extended conjugation to promote high charge carrier mobilities. The fDA-CP is prepared by the polycondensation of a plurality of at least one fused donor-acceptor oligomer (fDA-oligomer) that has a flat internal acceptor unit and at least one fused donor unit incorporated in the oligomers, and optionally, an additional conjugated aromatic monomer or oligomer copolymerized with the fDA-oligomers.