Formula I Donor Compounds for Organic Solar Cell Efficiency
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Solution Overview
Problem
Conventional organic solar cells face challenges in achieving high efficiency due to limited exciton diffusion length and the need for suitable semiconductor combinations that absorb a wide range of light, particularly in tandem cells, where materials with high open-circuit voltage and acceptable short-circuit current are required.
Innovation Solution
The use of specific compounds of formula (I) as donor or acceptor substances in a photoactive material, which form a donor-acceptor bilayer or mixed layer, paired with fullerene derivatives like C60, to enhance light absorption and exciton separation, thereby improving the efficiency of organic solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional organic solar cell materials are used, then the structure is simple and easy to manufacture, but the exciton diffusion length is limited and efficiency is low
Solution Approach 1:
The patent employs composite materials by combining specific donor compounds (formula I) with fullerene acceptors to create a bulk heterojunction photoactive layer. This composite structure optimizes both exciton diffusion and charge separation, resolving the contradiction between limited exciton diffusion length and low efficiency in conventional organic solar cells.
Solution Approach 2:
The patent applies local quality by creating distinct donor and acceptor phases within the photoactive layer, where each material is optimized for its specific function. The donor compounds (formula I) are designed with specific molecular structures to enhance exciton diffusion, while fullerene acceptors are positioned to maximize charge separation, allowing different regions to have specialized properties that collectively improve efficiency.
2Use of energy by moving object
If suitable semiconductor combinations are used to absorb wide range of light, then light absorption is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing donor compounds (formula I) that can be paired with various fullerene acceptors to create solar cells with different spectral responses. The general molecular structure of formula I allows for systematic modification to target different wavelength ranges, enabling one base compound class to serve multiple functions across the solar spectrum without requiring entirely different material systems.
Solution Approach 2:
The patent utilizes parameter changes by systematically modifying the molecular structure of donor compounds (formula I) through substitution patterns and side chain variations. These parameter changes allow tuning of absorption spectra, HOMO/LUMO energy levels, and molecular packing, enabling optimization of light absorption across different regions of the solar spectrum while maintaining compatibility with standard fullerene acceptors.
3Power
If high open-circuit voltage materials are used, then voltage is improved, but the short-circuit current may be reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the energy level parameters of donor compounds (formula I), specifically the HOMO and LUMO levels. By adjusting molecular structure parameters such as electron-withdrawing groups and conjugation length, the invention optimizes the energy level alignment between donor and acceptor to maximize open-circuit voltage while maintaining sufficient overlap for efficient charge transfer and acceptable short-circuit current.
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 described compounds and material configurations lead to improved light absorption and charge separation, resulting in enhanced efficiency and performance of organic solar cells, particularly in tandem cell configurations.
Implementation Method 1
Photovoltaic is understood to mean the direct conversion of radiative energy, principally solar energy, to electrical energy
Implementation Method 2
In organic solar cells, sufficiently high fields are unavailable, and so all existing concepts for organic solar cells are based on exciton separation at photoactive interfaces (organic donor-acceptor interfaces or interfaces to an inorganic semiconductor)
Data Source
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AI summary
The present invention relates to a photoactive material comprising a donor substance and an acceptor substance, wherein the donor substance comprises or consists of one or more compounds of formula (I) described below, or the acceptor substance comprises or consists of one or more compounds of formula (I) described below, or the donor substance comprises or consists of a first compound of formula (I) described below and the acceptor substance comprises a second compound of formula (I) described below with the proviso that the first and second compound are not the same, as well as to an organic solar cell or photodetector comprising said photoactive material. The present invention also relates to a photoelectric conversion device comprising or consisting of two or more organic solar cells comprising said photoactive material and to compounds of formula (I) as described below for use as donor substance or as acceptor substance in a photoactive material.