Polymer Hole-Transport Materials for Stable Inverted Perovskite Cells
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Solution Overview
Problem
Current hole-transport materials (HTMs) in perovskite solar cells (PSCs) lack the ability to be easily tuned for different perovskites, are difficult to process, and do not demonstrate high performance properties required for efficient hole extraction and charge separation, particularly in large-area devices under ambient conditions.
Innovation Solution
Development of polymer hole-transporting materials based on triarylamine and carbazole monomers, benzene or fluorene monomers, or fused carbazole monomers, which include phosphoric acid groups and cyano groups, to enhance stability and compatibility with perovskite inks, allowing for efficient hole transport and uniform coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current HTMs (PTAA, SAMs) are used in perovskite solar cells, then hole extraction and charge separation can be achieved, but device stability and efficiency are insufficient under ambient conditions
Solution Approach 1:
The patent employs composite polymer materials combining electron-donating groups (triarylamine, carbazole) with electron-accepting groups (phosphoric acid, cyano groups). This composite structure creates materials that simultaneously achieve high hole extraction efficiency through electron donation and enhanced stability through strong interfacial bonding via phosphoric acid groups with perovskite surfaces
Solution Approach 2:
The patent systematically varies molecular parameters including HOMO/LUMO energy levels, glass transition temperatures (Tg > 150°C), and functional group compositions to optimize both stability and efficiency. The polymer structures are designed with specific Tg values above 150°C and tailored energy levels to match perovskite bands, achieving enhanced stability without sacrificing charge transport
2Reliability
If HTMs are designed with high glass transition temperatures (Tg > 150°C) for stability, then device reliability improves, but processing difficulty increases
Solution Approach 1:
The patent designs polymers with specific molecular weight ranges and glass transition temperatures (Tg > 150°C) that maintain structural stability while remaining processable. The polymer architectures are engineered to exhibit appropriate viscosity and solution-processability characteristics despite the high Tg requirement, enabling fabrication through conventional coating techniques
Solution Approach 2:
The patent introduces flexible side chains and specific molecular architectures (linear, branched, or crosslinked structures) that provide local flexibility and processability while maintaining the overall high Tg structure for stability. The side chains with specific lengths and compositions enable solution processing without compromising the thermal stability of the main polymer backbone
3Reliability
If HTMs require passivation to address defects at the HTM-perovskite interface, then charge recombination is suppressed, but device complexity increases
Solution Approach 1:
The patent designs polymers where the phosphoric acid groups serve multiple functions simultaneously: they passivate interfacial defects through strong bonding with perovskite surfaces, facilitate charge separation through electron acceptance, and enhance structural stability. This multi-functionality eliminates the need for separate passivation layers, reducing device complexity while achieving effective defect suppression
Solution Approach 2:
The patent merges the passivation function with the hole transport function in a single polymer material. The phosphoric acid groups are integrated into the polymer backbone or side chains, combining the defect-passivating capability with the hole-transporting triarylamine and carbazole units, thereby simplifying the device structure while maintaining effective charge separation
4Productivity
If HTMs need to be tuned for different perovskites to achieve optimal performance, then efficiency improves, but ease of operation decreases
Solution Approach 1:
The patent establishes a systematic framework for tuning polymer parameters (HOMO/LUMO levels, side chain composition, functional group ratios) to match different perovskite compositions. The modular polymer design allows researchers to adjust specific parameters without redesigning the entire molecule, making it easier to optimize for various perovskites while maintaining high efficiency
Solution Approach 2:
The patent creates a universal polymer platform with phosphoric acid groups that can interface with multiple perovskite compositions. The electron-donating triarylamine and carbazole units provide universal hole-transporting capability, while the phosphoric acid groups offer universal passivation functionality across different perovskite types, reducing the need for complete material redesign
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 new polymer HTMs improve device stability and efficiency, enabling scalable production of high-performance inverted perovskite solar cells with improved wettability and crystallization of perovskite films under ambient conditions, overcoming the limitations of existing HTMs like PTAA and SAMs.
Implementation Method 1
A perovskite solar cell (PSC) is a type of solar cell that includes a perovskite-structured compound... PSCs are promising light-harvesting devices due to their high efficiencies
Implementation Method 2
Most commonly, these organic materials comprise small molecules and polymers containing the triarylamine moiety, which can be modified to match device needs. (Poly)arylamine-based materials are a frequent choice for HTMs in PSCs due to their electron-rich nature and high excited-state stability, which is attributable to resonance in adjacent conjugated groups
Implementation Method 3
The new polymer HTMs improve device stability and efficiency, enabling scalable production of high-performance inverted perovskite solar cells with improved wettability and crystallization of perovskite films under ambient conditions
Implementation Method 4
Current HTM lack in the ability to fulfill properties required for these applications such as high glass transition temperatures (Tg, above 150° C.), tunable energy levels (i.e., HOMO, LUMO) to match adjacent layers in the device
Data Source
AI summary
The present invention discloses several kinds of polymer hole-transporting material, comprising homopolymers or copolymers. The present invention also shows application in inverted-structure perovskite solar cells.