Interdigitated Back-Contact Perovskite Architecture for Charge Collection
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Solution Overview
Problem
Metal halide perovskite solar cells face challenges due to short electron-hole pair diffusion lengths, making it difficult to implement interdigitated back electrode structures, which are necessary for improved light harvesting and efficiency, and require a novel back electrode architecture and simple scalable processing method.
Innovation Solution
A back-contact optoelectronic device structure with a substrate featuring interdigitated hole- and electron-selective contacts, where the photoactive material is in contact with both electrodes, allowing for improved light absorption and efficient charge carrier collection, achieved through a one-step lithographic patterning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a standard sandwich configuration with TCO bottom contact is used, then the device structure is simple to manufacture, but light harvesting efficiency is reduced due to reflection, scattering, and absorption losses of nearly 15%
Solution Approach 1:
The patent inverts the conventional electrode configuration by placing both electron-selective and hole-selective contacts on the bottom substrate, with the photoactive layer deposited on top. This back-contact architecture eliminates the need for a TCO bottom contact that blocks light, allowing light to pass through the entire active area without reflection and scattering losses.
2Loss of energy
If interdigitated back electrode structure is implemented, then light harvesting efficiency is improved by eliminating TCO contact losses, but the short diffusion length of charge carriers in perovskites makes it difficult to achieve effective charge collection
Solution Approach 1:
The patent segments the bottom electrode into interdigitated finger-like patterns of electron-selective and hole-selective contacts, with spacing optimized to be within the charge carrier diffusion length. This segmentation allows carriers generated anywhere in the active layer to reach an electrode within their diffusion distance, solving the collection efficiency problem while maintaining the light harvesting benefits of the back-contact architecture.
3Reliability
If multiple deposition steps with large amounts of gold or silver are used in standard configuration, then electrode conductivity is ensured, but processing complexity and material cost increase
Solution Approach 1:
The patent merges the electron-selective and hole-selective contacts into a single bottom substrate layer, with both electrode types deposited in one processing step rather than separate steps. This integration simplifies the manufacturing process while ensuring both electrode types achieve adequate conductivity through the interdigitated finger pattern design.
4Loss of energy
If the top surface is completely exposed in back-contact configuration, then light absorption is maximized, but the device requires precise control of electrode spacing to match charge carrier diffusion length
Solution Approach 1:
The patent optimizes the electrode finger spacing parameter to match the charge carrier diffusion length of the specific perovskite material being used. By adjusting this critical parameter, the design achieves both maximum light absorption through complete top surface exposure and efficient charge collection, with the spacing typically set to be less than or equal to the diffusion length to ensure all carriers reach an electrode.
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 configuration enhances light harvesting efficiency, simplifies processing, and is suitable for building-integrated photovoltaics, with the potential for higher performance and reduced material usage compared to traditional configurations.
Implementation Method 1
Organic-inorganic perovskite solar cells have risen to the forefront of research into photovoltaic energy solutions
Implementation Method 2
If the diffusion length of the material in question is relatively long, however, it can be possible to mitigate these problems by making long and thin contacts with large spaces between them
Data Source
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AI summary
The present invention relates to an optoelectronic device comprising: (a) a substrate comprising at least one first electrode, which at least one first electrode comprises a first electrode material, and at least one second electrode, which at least one second electrode comprises a second electrode material; and (b) a photoactive material disposed on the substrate, which photoactive material is in contact with the at least one first electrode and the at least one second electrode, wherein the substrate comprises: a layer of the first electrode material; and, disposed on the layer of the first electrode material, a layer of an insulating material, which layer of an insulating material partially covers the layer of the first electrode material; and, disposed on the layer of the insulating material, the second electrode material, and wherein the photoactive material comprises a crystalline compound, which crystalline compound comprises: one or more first cations selected from metal or metalloid cations; one or more second cations selected from Cs+, Rb+, K+, NH4+ and organic cations; and one or more halide or chalcogenide anions. A substrate comprising a first and second electrode and processes are also described.