Donor-Acceptor Conjugated Polymers for High Mobility Solar Cells
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Solution Overview
Problem
Current donor-acceptor π-conjugated polymers for photovoltaic applications have limited absorption spectra and low charge carrier mobilities, hindering efficient solar energy conversion due to poor intermolecular interactions, chain-to-chain distances, and limited planarity, which restricts their use in viable light harvesting devices.
Innovation Solution
Development of donor-acceptor π-conjugated polymers with a specific structural design featuring solubilizing side chains, planar donor units, and spacer sequences that promote extended conjugation and favorable π-stacking, enabling high charge carrier mobilities and dual-band absorption in the visible spectrum, reflecting a green color and facilitating efficient charge transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If donor-acceptor π-conjugated polymers are used for photovoltaic applications, then absorption in the visible and NIR regions is achieved, but charge carrier mobilities remain low
Solution Approach 1:
The patent changes the structural parameters of the polymer by introducing planar donor units (such as selenophene, thiophene, pyrrole rings) and controlling the conjugation length and planarity of the polymer backbone. This structural parameter optimization enhances intermolecular π-stacking and charge transport pathways, achieving hole mobilities ≥1×10⁻⁶ cm²V⁻¹s⁻¹ while maintaining broad visible and NIR absorption
Solution Approach 2:
The patent creates composite polymer structures combining electron-rich donor units with electron-poor acceptor units in a donor-acceptor configuration. This composite molecular architecture enables simultaneous optimization of optical properties (broad absorption) and electrical properties (high charge carrier mobility) through controlled intermolecular interactions and π-stacking
2Use of energy by moving object
If green two-band absorbing polymers are designed, then dual-band absorption in visible region is achieved, but charge-carrier mobilities remain low due to poor intermolecular interactions
Solution Approach 1:
The patent optimizes structural parameters including the planarity of donor units, conjugation length, and side chain configuration to enhance π-stacking density and intermolecular interactions. This enables green two-band absorbing polymers to achieve hole mobilities ≥1×10⁻⁶ cm²V⁻¹s⁻¹, resolving the contradiction between optical properties and charge transport
3Reliability
If planar donor units with extended conjugation are introduced, then charge carrier mobility is improved, but solubility and processability may be reduced
Solution Approach 1:
The patent applies local quality modification by introducing solubilizing side chains at specific positions on the polymer backbone while maintaining the planarity of the core donor units. This localized modification enables high charge carrier mobility through π-stacking while simultaneously providing sufficient solubility for solution processing and fabrication
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 polymers achieve space-charge limited zero-field hole mobilities of at least 1×10−6 cm²V⁻¹s⁻¹, enhancing charge transport and solar energy conversion efficiency, with the ability to be processed in solutions or melts for scalable and cost-effective production of high-performance solar cells.
Implementation Method 1
The D2 units are of a structure that permits all atoms of the unit to reside in a single plane so that the space sequence can assume a conformation that yields extended conjugation and allows favorable stacking between DA polymers
Implementation Method 2
Two-band absorbing materials reflecting the color green are those that display two absorbance maxima in the visible light region with a window of transmission in the 480-560 nm range
Data Source
AI summary
A donor-acceptor (DA) π-conjugated polymer with high charge transfer mobility has a plurality of D1kAD1k portions, where k is 1 or 2, D1 is a donor unit having at least one solubilizing side chain, and A is an acceptor unit, and the donor-acceptor (DA) π-conjugated polymer has a plurality of D2m spacer sequences situated between the D1kAD1k portions, where m is 1 to 6 and D2 is a second donor unit where all atoms of the unit are coplanar in at least one conformation that the unit can assume. The DA π-conjugated polymer can reflect a blue tinted green, deep green, or yellow tinted green color. The DA π-conjugated polymers have space-charge limited (SCL) zero field hole mobilities of at least 1×10−6 cm2V−1s−1.