One-Donor Two-Acceptor Organic Solar Cells for Morphology Control
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Solution Overview
Problem
Ternary organic solar cells (OSC) face challenges in morphology control due to the complexity of three components, leading to lower performance compared to binary OSCs, with the best reported efficiency of about 10.3% still lagging behind binary devices.
Innovation Solution
A ternary OSC design using one donor polymer with strong temperature-dependent aggregation properties and two small molecular acceptors, which form an organic alloy, enabling improved morphology control and achieving a peak power conversion efficiency of 11.3% through simplified bulk heterojunction morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a ternary blend structure with three components is used to broaden absorption range, then the absorption breadth is improved, but the morphology control becomes extremely difficult and device performance decreases
Solution Approach 1:
The patent uses a single donor polymer instead of two different donors to create a more homogeneous blend system. This reduces the number of distinct phases and interactions that need to be controlled, making morphology management feasible while still achieving ternary blend functionality through the combination of one donor and two acceptors.
Solution Approach 2:
The patent employs a composite material approach by combining one donor polymer with two different acceptor materials (ITIC and IEIC) to create a ternary blend system. This composite structure allows broadening of absorption spectrum while maintaining relatively simple morphology control compared to two-donor systems, as the single donor provides a unifying matrix for the blend.
2Adaptability or versatility
If two donor polymers and one acceptor are used in ternary OSC, then absorption range is broadened, but the complicated morphology formed by two donors leads to lower performance
Solution Approach 1:
Instead of using two donors and one acceptor as in conventional ternary OSCs, the patent inverts the configuration to use one donor and two acceptors. This inversion resolves the morphology control issue by having a single donor phase that can more easily organize and interact with the two acceptor phases, leading to improved device performance of 11.3%.
3Adaptability or versatility
If a polymer and small molecular donor with one acceptor are used, then ternary OSC is formed, but morphology control challenges persist
Solution Approach 1:
The patent uses a homopolymer donor (PTB7-Th) rather than a copolymer or blend of two donors, creating a more homogeneous donor phase. This homogeneity simplifies the overall morphology control while still achieving effective ternary blend functionality through the combination with two different acceptor molecules.
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 ternary OSC achieves a record-high efficiency of 11.3% by leveraging the donor polymer's TDA properties to control morphology, resulting in improved fill factors and reduced trap-assisted recombination, with Voc exhibiting a linear increase with acceptor content.
Implementation Method 1
the donor polymer may exhibit temperature dependent aggregation (TDA) properties in solution, wherein the absorption onset of the polymer solution exhibits a red shift of at least 80 nm when the solution is cooled from 100° C. to room temperature
Implementation Method 2
one particular area of importance is the field of OSC. Organic semiconductors have found use in OSC because they allow devices to be manufactured by solution-processing techniques
Data Source
AI summary
An organic solar cell comprises a photoactive layer that comprises at least one donor polymer and two non-fullerene molecular acceptors. Further, an organic solar cell comprises a photoactive layer that comprises one donor polymer, one fullerene acceptor, and one non-fullerene molecular acceptor. The donor polymer may exhibit temperature dependent aggregation (TDA) properties in solution, wherein the absorption onset of the polymer solution exhibits a red shift of at least 80 nm when the solution is cooled from 100° C. to room temperature or the absorption onset of the polymer solution exhibits a red shift of at least 40 nm when the solution is cooled from 100° C. to 0° C.