Selective Emitter Solar Cell Impurity Grading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The efficiency of selective emitter solar cells is hindered by increased parallel resistance when the first electrode and first current collector are not correctly positioned on the second emitter portion, leading to a decrease in fill factor and overall efficiency.
Innovation Solution
A selective emitter solar cell design featuring a substrate with a second conductive type emitter layer having distinct impurity concentrations, where the second emitter portion includes specific regions that directly contact electrodes and current collectors, with optimized line widths and thicknesses to minimize misalignment and enhance contact resistance, thereby maintaining high conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emitter layer is doped with impurities of a low concentration, then the recombination of electrons and holes is reduced and the open-circuit voltage increases, but the contact resistance increases and the fill factor decreases
Solution Approach 1:
The emitter layer is divided into two regions with different impurity concentrations: a first emitter portion with low impurity concentration (lightly doped) to reduce recombination and increase open-circuit voltage, and a second emitter portion with high impurity concentration (heavily doped) to decrease contact resistance and increase fill factor. This local differentiation allows each region to optimize for its specific function.
2Manufacturing precision
If the emitter layer is doped with impurities of a high concentration, then the contact resistance decreases and the fill factor increases, but the open-circuit voltage decreases
Solution Approach 1:
The emitter layer is divided into two regions with different impurity concentrations: a first emitter portion with low impurity concentration (lightly doped) to reduce recombination and increase open-circuit voltage, and a second emitter portion with high impurity concentration (heavily doped) to decrease contact resistance and increase fill factor. This local differentiation allows each region to optimize for its specific function.
3Ease of manufacture
If the first electrode and first current collector are not formed at a correct location of the second emitter portion, then the manufacturing process becomes simpler, but the parallel resistance increases and the fill factor decreases
Solution Approach 1:
The second emitter portion is formed with predetermined line widths and geometric configurations before electrode deposition. This preliminary structuring creates built-in alignment guides that ensure electrodes are automatically positioned at correct locations during subsequent manufacturing steps, eliminating the need for complex positioning processes while maintaining low parallel resistance and high fill factor.
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 design maintains a predetermined conversion efficiency and fill factor by ensuring proper alignment and contact between the second emitter portion and electrodes/current collectors, preventing efficiency reduction due to misalignment while facilitating mass production.
Implementation Method 1
When light is incident on the solar cell having the above-described structure, electrons inside the semiconductors become free electrons (hereinafter referred to as 'electrons') by the photoelectric effect.
Data Source
AI summary
A manufacturing method of selective emitter solar cell can include, forming an emitter layer positioned on a light receiving surface of the substrate having a first conductive type, the emitter layer having a second conductive type opposite to the first conductive type, forming a first emitter portion having a first impurity concentration and a second emitter portion having a second impurity concentration higher than the first impurity concentration on the emitter layer using a etch stop mask or a mask pattern, and forming a plurality of first electrodes connected to the second emitter portion, wherein the second emitter portion includes a first region that contacts the first electrodes and overlaps the first electrodes and a second region that is positioned around the first region and does not overlap the first electrodes, and the line width of the second region is more than the line width of each first electrode and less than four times the line width of each first electrode.