Perovskite Solar Cell INI Contact Stack for Sputter Protection
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Solution Overview
Problem
Existing photovoltaic devices, particularly perovskite solar cells, face challenges with process reproducibility, carrier recombination, and material damage during manufacturing, especially due to the use of organic n-type contact layers and single SnO2 layers, which affect efficiency and reliability.
Innovation Solution
The introduction of an inorganic 'intrinsic-n-type-intrinsic' (INI) sandwich structure using Al2O3 as an electrically insulating layer, alongside SnO2, to enhance reproducibility, passivate interfaces, and protect against sputter damage, forming a trilayer stack that improves the stability and efficiency of perovskite solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single SnO2 layer is used to protect the organic n-type contact layer, then sputter protection is provided, but process reproducibility deteriorates due to run-to-run thickness variability of up to 10-15%
Solution Approach 1:
The single SnO2 layer is segmented into a trilayer structure consisting of Al2O3/SnO2/Al2O3. This segmentation allows each layer to perform specific functions: the first Al2O3 layer provides nucleation and protection, the SnO2 layer provides conductivity and sputter protection, and the second Al2O3 layer provides passivation. This resolves the contradiction by distributing functions across multiple layers, improving both protection reliability and manufacturing precision.
Solution Approach 2:
The invention uses a composite trilayer structure combining Al2O3 and SnO2 materials. This composite approach leverages the advantages of each material: Al2O3 provides excellent insulation and passivation properties, while SnO2 provides n-type conductivity and sputter protection. The composite structure achieves superior overall performance compared to a single material layer, resolving the contradiction between protection effectiveness and manufacturing consistency.
2Object-affected harmful factors
If an inorganic n-type layer is deposited to protect the organic n-type layer, then sputter damage is prevented, but carrier recombination at the interface increases due to unpassivated bonds
Solution Approach 1:
The second Al2O3 layer acts as an intermediary between the SnO2 layer and the organic n-type contact layer. This intermediary layer passivates the SnO2 surface, eliminating unpassivated bonds that would otherwise cause carrier recombination. Simultaneously, it maintains the protective function against sputter damage. This resolves the contradiction by introducing a mediating layer that eliminates harmful interface effects while preserving protection benefits.
Solution Approach 2:
The invention changes the interfacial properties by introducing Al2O3 layers with specific thicknesses (0.5-5 nm) and dielectric properties. By controlling the thickness and material properties of the Al2O3 layers, the interface is optimized to prevent carrier recombination while maintaining sputter protection. This parameter optimization resolves the contradiction between protection and energy loss.
3Reliability
If the inorganic layer density and surface coverage are increased to improve protection, then sputter protection effectiveness increases, but manufacturing complexity and process control difficulty increase
Solution Approach 1:
The first Al2O3 layer is deposited beforehand to create a controlled nucleation layer that ensures uniform SnO2 growth. This preliminary action establishes a consistent foundation that simplifies subsequent process control. By pre-establishing the interface structure, the invention achieves high protection effectiveness without proportionally increasing process complexity, as the preliminary layer guides subsequent deposition more reliably.
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 trilayer structure reduces run-to-run thickness variability, increases open-circuit voltage and fill factor, and enhances protection against sputter damage, leading to improved photovoltaic device performance and reliability.
Implementation Method 1
the two inorganic electrically insulative layers and the layer of conductive material therebetween are deposited in sequence onto the layer of n-type electron transporting material by atomic layer deposition
Implementation Method 2
the subsequent TCO (transparent conducting oxide electrode) layer is coated by sputtering onto the n-type contact
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A photovoltaic device comprises a PIN structure in which a p-type hole transporting layer (2) is carried by a substrate (1) and a perovskite layer (3) and an n-type electron transporting layer (4) are arranged in sequence on the p-type layer. A light transmissive electrically conductive layer (9) is provided on top of the n-type electron transporting layer to form a light receiving top surface. Between the n-type electron transporting layer and the light transmissive conductive layer there is provided a structure comprising two inorganic electrically insulative layers (6, 8) having a layer of a conductive material (7) therebetween, wherein the two inorganic electrically insulative layers comprise a material having a band gap of greater than 4.5 eV and the layer of a conductive material comprises a material having a band gap of less than the band gap of the electrically insulative layers, wherein each electrically insulative layer forms a type-1 offset junction with the layer of conductive material.