Perovskite Solar Cell Buffer Layer Mitigates Ion Migration
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Solution Overview
Problem
Perovskite solar cells face instability due to external factors like heat, oxygen, and moisture, as well as intrinsic instability from halide movement within the perovskite material, which affects their long-term performance and durability.
Innovation Solution
The use of 2D perovskites and ultra-thin atomic layer deposition (ALD) grown buffer layers mitigates ion migration and acts as a moisture barrier, confining halides within the perovskite layer and preventing their diffusion to charge transport layers, while also enhancing the device's encapsulation and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If perovskite solar cells are manufactured with simple solution-based fabrication techniques, then manufacturing cost is reduced and ease of manufacture is improved, but device stability and durability deteriorate due to intrinsic instability from halide movement
Solution Approach 1:
The patent introduces a buffer layer as an intermediary component between the perovskite absorber layer and the charge transport layers. This buffer layer mediates the interaction by confining halides within the perovskite layer and preventing their diffusion to the charge transport layers, thereby improving device stability while maintaining the simplicity of solution-based fabrication techniques.
Solution Approach 2:
The patent employs composite material structures by combining the perovskite absorber layer with a buffer layer and charge transport layers to create a multi-layered device architecture. This composite structure addresses the intrinsic instability of perovskites by integrating functional layers that work together to prevent halide migration while maintaining ease of manufacture through solution processing.
2Ease of operation
If perovskite solar cells operate under external environmental conditions (heat, oxygen, moisture), then device functionality is maintained, but extrinsic degradation occurs reducing device lifespan
Solution Approach 1:
The patent applies preliminary protective action by incorporating a buffer layer and encapsulation structures before the device is exposed to harsh environmental conditions. This preliminary protection prevents extrinsic degradation factors such as moisture and oxygen from directly attacking the perovskite layer, thereby extending device lifespan while maintaining functionality under operational conditions.
Solution Approach 2:
The patent creates a protected environment around the perovskite layer through encapsulation with protective layers that act as a barrier against external environmental factors. This effectively creates an inert environment that shields the sensitive perovskite material from heat, oxygen, and moisture, allowing the device to maintain functionality while significantly extending its operational lifespan.
3Stability of the object's composition
If halides are allowed to migrate within the perovskite material, then intrinsic instability is expressed, but device performance degrades due to diffusion to charge transport layers
Solution Approach 1:
The buffer layer serves as a mediator that physically separates the perovskite absorber layer from the charge transport layers. This intermediary structure prevents halides that migrate within the perovskite from reaching and degrading the charge transport layers, thereby maintaining both compositional stability and device performance.
Solution Approach 2:
The patent extracts the harmful effect of halide migration by introducing a buffer layer that selectively blocks halide diffusion to the charge transport layers. This extraction approach removes the degradation pathway while allowing the perovskite to maintain its compositional characteristics under operational conditions.
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
This approach significantly improves the stability and durability of perovskite solar cells by addressing both extrinsic and intrinsic degradation factors, leading to enhanced power conversion efficiency and extended device lifespan.
Implementation Method 1
ultra-thin atomic layer deposition (ALD) grown buffer layers mitigates ion migration and acts as a moisture barrier
Implementation Method 2
a perovskite layer configured, on photoexcitation, to generate photoexcited electrons and holes
Data Source
AI summary
A photoexcitable structure, comprising a lithiated nickel oxide (0.1-10% lithium) hole transport layer; a perovskite layer adjacent to the hole transport layer, configured, upon illumination, to generate photoexcited electrons and holes; an electron transport layer, and a buffer layer between the perovskite and ETL, configured to accept electrons from the buffer layer. The buffer layer is formed by atomic layer deposition, with a plurality of atomic layers of at least one resistive oxide having an aggregate thickness of less than 30 nm, configured to impede hole transfer from the perovskite to the electron transport layer, and impede ion migration and water diffusion. Beneath the HTL is a conductive layer or substrate. Above the ETL is an electrode. The entire structure is encapsulated. An alternate embodiment provides a buffer layer over the ETL.