ZnAlO Buffer Layer Mist Process for Solar Cells
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Solution Overview
Problem
Conventional buffer layers for solar cells, particularly those using cadmium and indium, are difficult to handle, costly, and have limited controllability over band gap, leading to increased production costs and inefficiencies in the solution growth method.
Innovation Solution
A method involving the formation of a Zn1-xAlxO buffer layer using a mist process with zinc and aluminum as metal raw materials, where x satisfies 0<x<1, allowing for precise control of band gap and resistivity by adjusting the aluminum to zinc ratio, and employing a misting technique that is simpler and less costly than traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cadmium or indium is used as buffer layer material, then the buffer layer can be formed with conventional solution growth method, but the production cost increases and handling becomes difficult due to waste disposal requirements
Solution Approach 1:
The patent replaces expensive and harmful materials (cadmium, indium) with inexpensive and environmentally friendly materials (zinc, aluminum). The buffer layer is formed using zinc oxide and aluminum oxide which are non-toxic, eliminating waste disposal issues while maintaining the buffer layer functionality.
Solution Approach 2:
The patent changes the material composition parameters by using zinc and aluminum instead of cadmium and indium. This parameter change transforms the buffer layer from harmful to environmentally friendly, while also reducing cost and improving ease of manufacture.
2Ease of manufacture
If indium is used as buffer layer material, then the buffer layer can be formed, but the production cost increases due to expensive raw material
Solution Approach 1:
The patent substitutes expensive indium with inexpensive zinc and aluminum. These common metals are abundant and low-cost, dramatically reducing the raw material cost while maintaining the buffer layer's essential properties for solar cell performance.
Solution Approach 2:
The patent changes the compositional parameters from rare/expensive metals to common/cheap metals. This parameter substitution achieves the same functional purpose at a fraction of the material cost.
3Ease of manufacture
If solution growth method is used to form buffer layer, then the buffer layer can be formed, but the production cost increases due to large amount of liquid waste disposal
Solution Approach 1:
The patent adopts spray pyrolysis method which uses minimal liquid and produces negligible waste compared to solution growth. The process uses aqueous solutions of zinc and aluminum salts that are sprayed in fine mist, evaporating quickly without requiring large volumes of liquid disposal infrastructure.
Solution Approach 2:
The patent replaces the solution growth method (chemical process requiring liquid handling and disposal) with spray pyrolysis (thermal/physical process). The substitution changes from chemical solution-based formation to aerosol spray-based formation, eliminating the need for large-scale liquid waste management.
4Manufacturing precision
If solution growth method is used to form buffer layer, then the buffer layer can be formed, but the controllability of band gap decreases resulting in variations between produced buffer layers
Solution Approach 1:
The patent changes the formation method parameters from solution growth to spray pyrolysis, which offers superior control over film composition and properties. The spray pyrolysis process allows precise control of deposition temperature, solution concentration, and spray rate, enabling accurate and consistent band gap control.
Solution Approach 2:
The spray pyrolysis method provides better process control and reproducibility, allowing for consistent band gap values across different buffer layers. The method enables real-time adjustment of deposition parameters to maintain precise control over the buffer layer properties.
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 production of a buffer layer with controlled band gap and resistivity over a wide range, reducing production costs and environmental impact while maintaining high transparency and ease of handling, thus improving solar cell efficiency and cost-effectiveness.
Implementation Method 1
forming a solution containing zinc and aluminum as metal raw materials of the buffer layer into a mist
Implementation Method 2
heating a substrate disposed in the atmosphere
Implementation Method 3
spraying a mist of the solution atomized in the step (A) to the substrate in the step (B)
Data Source
AI summary
A method for film-forming a buffer layer to be used for a solar cell, the buffer layer being disposed between a light absorbing layer and a transparent conductive film. Specifically, in this buffer layer film-forming method, a solution is formed into a mist, the solution containing zinc and almuminum as metal raw materials of the buffer layer. Then, a substrate disposed in the atmosphere is heated. Then, the mist of the solution is sprayed to the substrate being heated.