Inverted Layer Sequence Organic Solar Cell
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Solution Overview
Problem
In organic solar cells, the 'floating' of the donor material during deposition or post-treatment in mixed layers leads to transport problems at the interface, counteracting the benefits of improved order and crystallinity, especially when the donor material has a significantly lower evaporation temperature than the acceptor material, resulting in poor electron transport and reduced efficiency.
Innovation Solution
An inverted layer sequence (nip, ip, or ni structure) is adopted, where photogenerated electrons leave the mixed layer in the direction of the substrate, and the structure is optimized with suitable contact systems and doping to prevent blocking effects, ensuring low-loss recombination and efficient charge transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the donor material has a significantly lower evaporation temperature than the acceptor material, then the donor material floats during deposition, but this leads to transport problems at the interface and poor electron transport
Solution Approach 1:
The patent inverts the conventional layer sequence from p-i-n to n-i-p structure. This inversion changes the deposition order so that the acceptor material is deposited first, followed by the donor material, preventing the donor from floating to the interface and causing transport problems.
Solution Approach 2:
The patent changes the deposition parameters by inverting the layer sequence, which fundamentally alters the deposition process. This parameter change ensures that the donor material with lower evaporation temperature does not float to the interface, resolving the transport problem while maintaining layer order.
2Ease of manufacture
If the donor material floats during deposition, then the mixed layer forms, but transport problems occur at the interface
Solution Approach 1:
By inverting the layer sequence to n-i-p, the patent prevents the donor material from floating to the interface during deposition. This inversion maintains the mixed layer structure for ease of manufacture while eliminating the interface transport problems that would otherwise occur.
3Reliability
If the inverted layer sequence is used, then electron transport is improved, but the structure complexity increases
Solution Approach 1:
The patent applies a simple inversion of the conventional p-i-n structure to create an n-i-p structure. This single structural change improves electron transport by preventing donor floating, while the overall device complexity remains relatively low since it only requires changing the deposition sequence and contact assignments.
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 enhances the efficiency and service life of the organic solar cells by minimizing transport issues and maintaining good order in the mixed layer, leading to improved photocurrent generation and fill factor.
Implementation Method 1
A solar cell converts light energy into electrical energy. The term photoactive here also refers to the conversion of light energy into electrical energy.
Implementation Method 2
The excitons reach such an active interface by diffusion, where electrons and holes are separated from one another.
Implementation Method 3
The material that takes up the electrons is called the acceptor, and the material that takes up the hole is called the donor (or donor). The separating interface can be between the p (n) layer and the i layer or between two i layers.
Implementation Method 4
In the built-in electrical field of the solar cell, the electrons are now transported away to the n-area and the holes to the p-area.
Data Source
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AI summary
The invention relates to a photoactive component comprising organic layers, in particular a solar cell comprising a photoactive i-layer system, which contains at least one mixed layer, wherein said mixed layer contains at least one donator material and one acceptor material, and thus forms a donator-acceptor system. The donator material and the acceptor material of the mixed layer are non-polymer materials. In a vacuum, the donator material has an evaporation temperature which is at least 150 °C lower than the evaporation temperature of the acceptor material and has an inverted layer sequence with an n-i-p, i-p, or n-i structure of an n-layer, i-layer, or p-layer system respectively, wherein the organic photoactive i-layer system is applied directly onto the cathode or onto an electron-conducting n-material system.