Ionic Compound for Perovskite Solar Cell Hole Transport
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Solution Overview
Problem
Existing ionic compounds used in applications such as perovskite solar cells require improvements in cation reactivity, particularly for enhancing open circuit voltage, durability, and service life, with conventional additives like quaternary ammonium or pyridine having limited electron orbital spread and cationicity.
Innovation Solution
Development of an ionic compound comprising an organic ammonium cation with 1 to 20 carbon atoms and a fluorine-containing bis(sulfonyl)imide anion, which reacts spontaneously with the perovskite layer to improve electrical bonding and hole mobility, reducing defects and allowing production in air atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ionic compounds (quaternary ammonium or pyridine) are used as dopants, then hole mobility is improved, but cation reactivity and electron orbital spread are limited
Solution Approach 1:
The patent changes the chemical parameters of the cation by introducing organic ammonium cations with specific carbon chain lengths (1-20 carbons) and structures. This parameter change increases electron orbital spread and cation reactivity while maintaining hole mobility enhancement, directly resolving the contradiction between reliable charge transport and adaptive chemical reactivity
Solution Approach 2:
The patent creates a composite ionic compound by combining organic ammonium cations with fluorine-containing bis(sulfonyl)imide anions. This composite structure synergistically provides both the hole mobility improvement from ionic doping and the enhanced reactivity from the organic cation's electron orbital spread, simultaneously achieving both desired properties
2Reliability
If 4-tert-butylpyridine is added to dopant, then hole mobility is improved, but heat resistance deteriorates due to low boiling point
Solution Approach 1:
The patent changes the thermal parameter by selecting ionic compounds with appropriate melting points and thermal stability. The organic ammonium cations with 1-20 carbon atoms provide tunable thermal properties, allowing selection of compounds that maintain hole mobility enhancement while possessing sufficient heat resistance for solar cell operation, resolving the contradiction between electrical performance and thermal stability
3Productivity
If perovskite layer is made hydrophilic, then photoelectric conversion efficiency is improved, but durability deteriorates due to hydrate formation
Solution Approach 1:
The patent applies local quality modification by using ionic compounds that create localized hydrophobic environments at the perovskite interface while maintaining bulk hydrophilicity for charge transport. The organic ammonium cations provide local steric protection and hydrophobic character at critical interfaces, preventing hydrate formation in specific locations without sacrificing overall photoelectric conversion efficiency
Solution Approach 2:
The ionic compound acts as an intermediary layer between the hydrophilic perovskite and the external environment. The organic ammonium cation mediates by providing both ionic conductivity for efficient charge extraction and hydrophobic protection against moisture ingress, simultaneously enabling high photoelectric conversion and durability through its dual functional character
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 ionic compound enhances the performance and durability of perovskite solar cells by improving open circuit voltage and reducing production environment constraints, enabling production in air without inert atmospheres.
Implementation Method 1
reacts spontaneously with the perovskite layer to improve electrical bonding
Implementation Method 2
Adding such a dopant to the hole-transporting material facilitates the movement of the holes
Data Source
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AI summary
The present invention provides an ionic compound including a molecular cation and a molecular anion, wherein the molecular cation includes at least one organic ammonium selected from the group consisting of a primary organic ammonium, a secondary organic ammonium, and a tertiary organic ammonium, wherein the organic ammonium has an organic moiety having 1 to 20 carbon atoms, and wherein the molecular anion includes a fluorine-containing bis(sulfonyl)imide.