Textured Solar Cell Junction Layout With Fewer Diffusion Steps
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Solution Overview
Problem
Existing methods for manufacturing solar cells with high photoelectric conversion efficiency are costly due to numerous steps, thermal treatment, and difficulty in forming uniform masks, leading to increased contact resistance and reduced minority carrier lifetime.
Innovation Solution
A method involving the formation of unevenness on both surfaces of a semiconductor substrate, reducing the number of steps by forming an emitter layer and base layer with a higher dopant concentration, and using a dielectric film to lower contact resistance between electrodes, thereby improving photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mask forming and opening steps are performed to create emitter and base layers, then the solar cell structure can be formed, but the production cost increases and the number of steps increases
Solution Approach 1:
The patent combines the formation of emitter and base layers into a single diffusion step by applying a dopant that simultaneously creates both P-type and N-type regions. The dopant diffuses to form a P-type emitter layer in one area and an N-type base layer in another area during the same thermal processing step, eliminating the need for separate mask formation and diffusion steps for each layer.
Solution Approach 2:
The dopant serves multiple functions: it acts as both a masking agent and a diffusion source, and it creates both P-type and N-type semiconductor regions simultaneously. This multi-functional approach replaces the conventional multi-step process requiring separate masks and dopant applications.
2Manufacturing precision
If thermal treatment steps are increased to form layers and patterns, then the solar cell structure is achieved, but the minority carrier lifetime is reduced
Solution Approach 1:
The dopant is pre-applied to the substrate surface before the diffusion step. This preliminary doping allows the subsequent thermal treatment to simply activate and diffuse the already-present dopant, rather than requiring prolonged high-temperature processing to both deposit and diffuse the dopant simultaneously, thereby reducing the overall thermal exposure time.
3Manufacturing precision
If conventional diffusion masking methods are used, then patterned layers can be formed, but uniform masks are difficult to form and contact resistance increases
Solution Approach 1:
The patent changes the physical and chemical parameters of the dopant application process to achieve uniform coverage. By controlling the dopant solution concentration, application method, and subsequent diffusion parameters, the process achieves uniform dopant distribution that forms consistent P-type and N-type regions with low contact resistance.
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 method decreases production costs and enhances photoelectric conversion efficiency by reducing contact resistance and maintaining high minority carrier lifetime, resulting in a more efficient solar cell manufacturing process.
Implementation Method 1
forming an emitter layer of a second conductivity type which is an opposite conductivity type to the first conductivity type, on a first main surface of the semiconductor substrate; forming a base layer of the first conductivity type, having a dopant concentration higher than in the semiconductor substrate
Implementation Method 2
forming a dielectric film on the first main surface; forming a base electrode on the base layer; and forming an emitter electrode on the emitter layer
Data Source
AI summary
A method for manufacturing a solar cell, including the steps of: forming unevenness on both of main surfaces of a semiconductor substrate of a first conductivity type; forming an emitter layer on a first main surface of the semiconductor substrate; forming a diffusion mask on the emitter layer; removing the diffusion mask in a pattern; forming a base layer on the portion where the diffusion mask have been removed; removing the remaining diffusion mask; forming a dielectric film on the first main surface; forming a base electrode on the base layer; and forming an emitter electrode on the emitter layer. This provides a method for manufacturing a solar cell that can bring high photoelectric conversion efficiency while decreasing the number of steps.