High-Purity Fullerene Derivative for Stable Organic Solar Cells
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Solution Overview
Problem
Current fullerene derivatives for organic thin-film solar cells, except for [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), have not demonstrated high and stable photoelectric conversion efficiency, limiting the development of advanced n-type semiconductor materials.
Innovation Solution
A fullerene derivative with a purity of ≥99% is developed, represented by formula (1), where ring A is C60 fullerene, R1 is C1-6 alkyl or naphthyl optionally substituted with halogen, and Ar is phenyl or naphthyl optionally substituted with C1-8 alkyl groups, combined with a donor-acceptor type π-conjugated polymer, enhancing photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fullerene derivatives other than PCBM are used as n-type semiconductor materials, then structural diversity and potential performance improvement are achieved, but stable and high photoelectric conversion efficiency has not been demonstrated
Solution Approach 1:
The patent systematically varies key structural parameters of fullerene derivatives including substituent types (alkyl chains of different lengths, aromatic groups), substitution positions (mono-, di-, tri-substituted), and molecular weight to optimize photoelectric conversion efficiency while maintaining stability, moving beyond PCBM's fixed structure
Solution Approach 2:
The patent creates composite material systems by combining specific fullerene derivative n-type semiconductors with p-type semiconductor polymers (such as P3HT, PTB7) to form bulk heterojunction structures, where the composite interface enables efficient charge separation and transport while achieving both high efficiency and stability
2Productivity
If bulk heterojunction structure is used in organic thin-film solar cells, then photoelectric conversion efficiency increases significantly, but device complexity and material selection requirements increase
Solution Approach 1:
The patent optimizes the local properties of the bulk heterojunction by carefully selecting fullerene derivatives with specific molecular weights, solubility characteristics, and crystallinity to ensure proper phase separation and domain morphology at the nanoscale, enabling efficient charge separation while managing device complexity through targeted material design
3Ease of manufacture
If conventional fullerene derivative synthesis methods are used, then production is achieved, but yield and purity are limited
Solution Approach 1:
The patent employs preliminary purification actions during synthesis including column chromatography and recrystallization steps to remove impurities and side products early in the process, ensuring high purity of the fullerene derivative materials before device fabrication, thereby achieving both manufacturing feasibility and high purity
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 organic power-generating layer achieves high photoelectric conversion efficiency and easy film formation, forming a bulk heterojunction structure for improved solar cell performance.
Implementation Method 1
Organic thin-film solar cells are formed by a coating technique with a solution of an organic compound, which is a photoelectric conversion material
Implementation Method 2
the use of the bulk heterojunction structure has particularly led to a significant increase in photoelectric conversion efficiency
Data Source
AI summary
The object of the present invention is to provide a material having excellent performance as an n-type semiconductor material, in particular an n-type semiconductor for photoelectric conversion elements such as organic thin-film solar cells. The present invention provides an n-type semiconductor consisting of a fullerene derivative having a purity of 99% or more as defined below, the fullerene derivative being represented by formula (1): wherein ring A represents C60 fullerene; R1 represents a hydrogen atom, alkyl optionally having at least one substituent, or aryl optionally having at least one substituent; and Ar represents aryl optionally substituted with at least one alkyl group, the purity being defined by the following equation: Purity%=100−Dmax% wherein the Dmax (%) is the maximum value among the absolute value of the difference between an analysis value and a theoretical value obtained in elemental analysis of carbon, the absolute value of the difference between an analysis value and a theoretical value obtained in elemental analysis of hydrogen, and the absolute value of the difference between an analysis value and a theoretical value obtained in elemental analysis of nitrogen.