Solar Cell Two-Stage Emitter Dopant Control
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Solution Overview
Problem
Current methods for manufacturing solar cells using thermal diffusion and screen printing face limitations in improving conversion efficiency due to high surface dopant concentration, leading to increased contact resistance and reduced reliability, while complex processes and high costs are associated with attempts to form two-stage emitters for efficiency enhancement.
Innovation Solution
A method involving the simultaneous formation of high-concentration and low-concentration diffusion layers using distinct coating materials with dopants and scattering agents, preventing out-diffusion and autodoping, allows for a simple and cost-effective manufacturing process with maintained high production yield and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface concentration of dopant in diffusion layer is increased to reduce contact resistance, then electrical conductivity is improved, but conversion efficiency deteriorates due to excessive recombination
Solution Approach 1:
The patent applies local quality by creating a two-stage emitter structure where the diffusion layer has different dopant concentrations at different depths. The first stage forms a high-concentration region (1E+20 to 1E+21 atoms/cm³) for low contact resistance, while the second stage forms a low-concentration region (1E+19 to 1E+20 atoms/cm³) for reduced recombination. This spatial variation in dopant concentration optimizes both electrical conductivity and conversion efficiency simultaneously.
2Ease of manufacture
If thermal diffusion method is used to form diffusion layer, then manufacturing process is simplified, but dopant concentration distribution becomes difficult to control precisely
Solution Approach 1:
The patent applies preliminary action by performing a first thermal diffusion treatment to form a high-concentration dopant layer, followed by a second thermal diffusion treatment to form a low-concentration dopant layer. This sequential approach allows precise control of dopant concentration distribution at different depths, achieving the two-stage emitter structure with specified concentration ranges while maintaining the simplicity of thermal diffusion processing.
3Productivity
If compound including dopant is added around silver filler to improve contact, then conversion efficiency is improved, but fill factor and reliability decrease due to unstable contact
Solution Approach 1:
The patent extracts the problematic dopant compound from the electrode paste formulation and instead delivers dopant directly to the diffusion layer through controlled thermal diffusion treatments. This eliminates the unstable interface layer between dopant compound and silver filler, ensuring stable ohmic contact while achieving the desired dopant concentration profile in the silicon substrate for high conversion efficiency.
4Productivity
If two-stage emitter is formed by adding dopant compound around silver filler, then conversion efficiency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies self-service by using the electrode paste as a mask during thermal diffusion treatments. The paste naturally defines the electrode regions, and dopant diffuses through and around the paste to form the two-stage emitter structure automatically. This eliminates the need for separate masking steps and complex alignment processes, reducing manufacturing complexity while achieving precise dopant concentration control for high conversion efficiency.
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 high-performance solar cells with improved conversion efficiency and reduced manufacturing costs by forming two-stage emitters with precise surface concentration control, enhancing both efficiency and yield.
Implementation Method 1
a first diffusion layer formed by coating the first coating material, and a second diffusion layer formed by coating the second coating material, the second diffusion layer having a conductivity is different from that of the first diffusion layer are simultaneously formed by a diffusion heat treatment
Implementation Method 2
after coating the first coating material containing the dopant and an agent for preventing a dopant from scattering
Implementation Method 3
an agent for preventing autodoping are coated on the semiconductor substrate
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3~4
AI summary
The present invention is a method for manufacturing a solar cell by forming a p-n junction in a semiconductor substrate having a first conductivity type, wherein, at least: a first coating material containing a dopant and an agent for preventing a dopant from scattering, and a second coating material containing a dopant, are coated on the semiconductor substrate having the first conductivity type so that the second coating material may be brought into contact with at least the first coating material; and, a first diffusion layer formed by coating the first coating material, and a second diffusion layer formed by coating the second coating material the second diffusion layer having a conductivity is lower than that of the first diffusion layer are simultaneously formed by a diffusion heat treatment; a solar cell manufactured by the method; and a method for manufacturing a semiconductor device. It is therefore possible to provide the method for manufacturing the solar cell, which can manufacture the solar cell whose photoelectric conversion efficiency is improved at low cost and with a simple and easy method by suppressing surface recombination in a portion other than an electrode of a light-receiving surface and recombination within an emitter while obtaining ohmic contact; the solar cell manufactured by the method; and the method for manufacturing the semiconductor device.