Perovskite Layer Drying with Dual Protic Solvents for Fast Coating
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Solution Overview
Problem
Current methods for producing perovskite solar cells are limited by slow deposition and drying speeds, leading to high capital equipment costs and inefficiencies, particularly due to the use of polar, aprotic solvents which result in poor morphology and pinhole defects in larger areas, making it challenging to achieve scalable, low-cost production that competes with silicon-based technologies.
Innovation Solution
A dual solvent system of polar, protic solvents with low boiling points is used for the deposition and drying of perovskite solutions, allowing for high-speed processing at temperatures between 20 to 40 degrees Celsius, with a multi-stage drying process that promotes uniform crystal growth and reduces the need for extensive annealing, thereby enabling the production of defect-free perovskite layers on flexible substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional spin-coating method is used to fabricate perovskite solar cells, then high power conversion efficiency can be achieved, but production speed is too slow for scalable manufacturing
Solution Approach 1:
The drying process is divided into multiple stages with different air flow conditions. The first stage uses high air flow for rapid solvent removal, followed by a second stage with reduced air flow for controlled crystallization. This segmentation allows the process to achieve both high speed and high quality perovskite layers.
2Productivity
If fast drying is used to increase production speed, then deposition time is reduced, but pinhole defects increase due to poor wetting and non-uniform crystal growth
Solution Approach 1:
The perovskite precursor solution is pre-formulated with optimized solvent composition and precursor ratios to ensure proper wetting and nucleation. The solution is prepared with specific solids concentration (30-70% of saturation) to enable rapid deposition while maintaining film quality. This preliminary preparation allows fast drying without compromising uniformity.
Solution Approach 2:
The drying process is divided into multiple stages with different air flow conditions. The first stage uses high air flow for rapid solvent removal, followed by a second stage with reduced air flow for controlled crystallization. This segmentation allows the process to achieve both high speed and high quality perovskite layers.
3Area of stationary object
If scalable deposition techniques are used to increase production capacity, then manufacturing area is expanded, but deposition and drying speeds remain insufficient for cost-competitive production
Solution Approach 1:
The perovskite precursor solution is pre-formulated with optimized solvent composition and precursor ratios to ensure proper wetting and nucleation. The solution is prepared with specific solids concentration (30-70% of saturation) to enable rapid deposition while maintaining film quality. This preliminary preparation allows fast drying without compromising uniformity.
4Manufacturing precision
If anti-solvent method is used to improve crystallization, then crystal growth is enhanced, but process complexity and cost increase due to additional steps
Solution Approach 1:
The invention extracts and eliminates the anti-solvent step from the traditional process. By optimizing the precursor solution formulation and using controlled air flow drying, the process achieves good crystal growth without requiring additional anti-solvent handling, dispensing, and thermal annealing steps.
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 enables the rapid and uniform production of high-efficiency perovskite layers on flexible substrates, reducing equipment costs and improving the scalability of perovskite solar cells, while maintaining stability and safety during handling and storage.
Implementation Method 1
A scalable, high-speed method for the solution-processing of a perovskite layer is disclosed. The method comprises the deposition and drying of a perovskite solution... the drying is multi-stage... the solution comprises dual polar, protic solvents
Implementation Method 2
pinhole gaps between perovskite crystals result from poor-wetting of the solution and non-uniform crystal growth during film formation
Implementation Method 3
pinhole gaps between perovskite crystals result from poor-wetting of the solution and non-uniform crystal growth during film formation
Data Source
AI summary
A method for making a perovskite layer includes providing a substrate; providing a perovskite solution comprising first and second polar, protic solvents each having a boiling point less than 135 degrees Celsius, an inorganic perovskite precursor, and an organic perovskite precursor, wherein the first solvent is an alcohol-based glycol ether capable of dissolving the inorganic Perovskite precursor material, the second solvent is an aliphatic alcohol, and the perovskite solution has a total initial amount of solvent greater than 30 percent by weight and a total solids concentration that is between 30 percent and 70 percent by weight of the Perovskite solution's saturation concentration: depositing the perovskite solution at a temperature of from 20 to 40 degrees Celsius on the substrate at a first location; removing a first portion of the initial amount of solvent from the deposited perovskite solution with a first drying step having a first drying step dwell time at a second location wherein the temperature of the first drying step is maintained between 20 and 40 degrees Celsius and the first drying step increases the total solids concentration of the perovskite solution to at least 75 percent of its saturation concentration; and removing a second portion of the initial amount of solvent from the deposited perovskite solution with a second drying step having a higher rate of solvent evaporation than the first drying step during a second drying step dwell time at a third location that causes saturation and a conversion reaction in the deposited perovskite solution resulting in perovskite crystal formation or formation of a perovskite intermediate phase, wherein the substrate is moved at a constant speed from the first location to the second location, and from the second location to the third location. A continuous inline method for production of photovoltaic devices at high speed, and a perovskite solution for use in making a uniform Perovskite layer at high speed to enable low cost production of high efficiency Perovskite devices are also described.