Perovskite Solar Cell Passivation to Block Lithium Ion Migration
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Solution Overview
Problem
Perovskite solar cells exhibit poor long-term stability due to lithium ion migration, despite using conventional passivation materials that can be easily traversed by lithium ions, leading to performance degradation.
Innovation Solution
A passivation layer comprising an amide and/or its cation, specifically compounds of formulas (1) and (2), is introduced between the hole transport layer and the perovskite layer, which includes organic acids or inorganic acids to stabilize the perovskite phase and prevent lithium ion migration, utilizing an alkyl chain instead of cyclic structures to block lithium ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional passivation materials are used, then photoelectric conversion efficiency is improved, but long-term stability deteriorates due to lithium ion migration
Solution Approach 1:
The patent introduces a passivation layer comprising amide compounds as an intermediary between the perovskite layer and hole transport layer. This intermediate layer specifically blocks lithium ion migration while maintaining charge carrier transport, thus resolving the contradiction between efficiency and stability by mediating the interaction between electrodes and perovskite.
Solution Approach 2:
The patent changes the chemical composition parameters of the passivation layer by using amide compounds with specific molecular structures (containing carbonyl and amino groups) rather than conventional materials. This parameter change enables selective ion blocking while maintaining electrical functionality, thereby improving long-term stability without sacrificing photoelectric conversion efficiency.
2Productivity
If passivation materials are used to improve efficiency, then device performance is enhanced, but harmful lithium ion migration increases
Solution Approach 1:
The patent converts the harmful effect of lithium ion migration into a beneficial outcome by designing a passivation layer that specifically targets and blocks lithium ions while allowing beneficial charge carriers to pass. The amide compounds' molecular structure is optimized to create a barrier that selectively prevents harmful ion migration while maintaining device functionality.
3Stability of the object's composition
If cyclic structures are used in passivation materials, then material stability is improved, but lithium ion blocking capability deteriorates
Solution Approach 1:
The patent inverts the conventional approach by using linear/branched alkyl chain structures instead of cyclic structures in the amide compounds. This structural inversion achieves better lithium ion blocking capability while maintaining material stability through the specific arrangement of carbonyl and amino groups in the molecular chain.
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 proposed solution enhances the long-term stability and photoelectric conversion efficiency of perovskite solar cells by effectively passivating defects and anchoring lithium ions, thereby reducing adverse effects on the device's performance.
Implementation Method 1
a nitrogen atom on the amide has a strong ability to bind protons, so it is not easy to generate harmful hydrogen vacancy during use
Implementation Method 2
oxygen on the amide can be well anchored with lead in perovskite (if there is lead), which fixes the structure of an iodide-lead octahedron, so as to stabilize a perovskite phase
Implementation Method 3
due to p-π conjugation, the amide has a strong electron cloud density, which can stabilize a lithium ion and prevent the lithium ion from migrating into the perovskite
Data Source
Figure 1
AI summary
The present application provides a perovskite solar cell, including conductive glass, a hole transport layer, a perovskite layer, an electron transport layer and a back electrode, where a passivation layer is disposed between the hole transport layer and the perovskite layer, and the passivation layer includes an amide and/or a cation thereof, where the amide includes a compound of formula (1) and/or formula (2): where R1 and R2 are each independently selected from hydrogen, -R, -NR2, -NHR, -NH2, - OH, -OR, -NHCOR, -OCOR, and -CH2COOH, where R represents a straight or branched chain alkyl group having 1-10 carbon atoms, m is an integer of 0 to 10; and n is an integer of 1 to 10; and where Ar is selected from a C5-C10 aryl or heteroaryl group, optionally, pyridine, pyran, thiopyran, benzene, naphthalene, quinoline, isoquinoline, pyrrole, pyrazole, pyrimidine, pyrazine, pyridazine, and isoindole. The perovskite solar cell provided by the present application has higher photoelectric conversion efficiency and better long-term stability.