DPP Derivatives for High-Efficiency Organic Solar Cells
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Solution Overview
Problem
Current organic semiconductor materials, particularly small molecule-based solar cells, face challenges in achieving high power conversion efficiency (PCE), field effect mobility, on/off current ratio, and low threshold voltage, limiting their performance in devices like solar cells and organic field effect transistors.
Innovation Solution
Development of specific diketopyrrolopyrrole (DPP) derivatives with longer side chains, which exhibit improved solubility, ease of synthesis, and purification, are used as organic semiconductors in solar cells and field effect transistors, enhancing their performance by optimizing the donor-acceptor ratio and using nickel oxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If small molecule-based organic semiconductors are used in solar cells, then lower cost fabrication and compatibility with flexible substrates are achieved, but power conversion efficiency remains much lower than silicon-based cells
Solution Approach 1:
The patent modifies molecular parameters by introducing specific side chain structures (alkyl groups with 7 or more carbon atoms) on the DPP nitrogen atoms, which fundamentally changes the material's electronic and optical properties. This enables small molecules to achieve PCE exceeding 4%, resolving the efficiency limitation while maintaining solution processability and low-cost fabrication advantages
Solution Approach 2:
The patent creates composite semiconductor materials by combining DPP core structures with specifically designed side chains (such as thienyl groups with alkyl substituents). This composite molecular architecture optimizes both the electronic properties for high efficiency and the solubility for easy processing, achieving high PCE without sacrificing manufacturing ease
2Ease of operation
If small molecule-based organic semiconductors are used, then solution processing and ease of purification are achieved, but power conversion efficiency and field effect mobility remain low
Solution Approach 1:
The patent applies local quality by differentiating the functions of different molecular regions: the DPP core provides electronic activity and charge transport, while the side chains (with 7+ carbon atoms) provide solubility and processability. This spatial differentiation of functions allows the molecule to simultaneously achieve high efficiency and easy handling
Solution Approach 2:
By changing the side chain parameters (carbon atom count ≥7, specific structural motifs), the patent optimizes the balance between solubility and electronic properties. The side chains provide sufficient solubility for solution processing while their electronic structure contributes to high charge carrier mobility and PCE
3Ease of manufacture
If conventional DPP derivatives with short side chains are used, then synthesis is easier, but power conversion efficiency and field effect mobility are limited
Solution Approach 1:
The patent systematically varies the side chain parameters (length, branching, functional groups) to find the optimal balance. By requiring 7 or more carbon atoms in the side chains, the patent achieves a threshold effect where both synthesis remains feasible and device performance dramatically improves, with PCE exceeding 4%
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 DPP derivatives achieve exceptionally high PCEs exceeding 4%, along with high field effect mobility and low threshold voltage, significantly improving the performance of solar cells and organic field effect transistors.
Implementation Method 1
the power conversion efficiency (PCE), i.e. the the percentage of power converted from absorbed light to electrical energy
Data Source
AI summary
The present invention relates to compounds of the formula Iwherein the substituents are as defined in claim 1, and their use as organic semiconductor in organic devices, like diodes, organic field effect transistors and/or a solar cells.The compounds of the formula I have excellent solubility in organic solvents. High efficiency of energy conversion, excellent field-effect mobility, good on/off current ratios and/or excellent stability can be observed, when said compounds are used in semiconductor devices or organic photovoltaic (PV) devices (solar cells).