Backside Solar Cell Emitters With Dotted Diffusion and Asymmetric Layouts
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Solution Overview
Problem
Conventional solar cell manufacturing techniques face challenges in achieving high efficiency due to carrier recombination issues at diffused trenches and metal-contacted doped regions, which affect the voltage and current production of solar cells.
Innovation Solution
The implementation of a dotted-diffusion design with differentiated P-type and N-type layouts, utilizing laser ablation and self-alignment processes to form non-overlapping dots as emitters, reduces carrier recombination and improves breakdown voltage, enabling more uniform ablation and side-wall control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional emitter patterning methods are used, then manufacturing process is simpler, but material removal is difficult and manufacturing throughput is reduced
Solution Approach 1:
The patent replaces conventional mechanical or chemical etching methods with laser ablation technology. The laser beam directly removes material through localized heating and vaporization, eliminating the need for complex chemical etchants and multiple processing steps. This substitution of mechanical/chemical systems with optical energy delivery significantly improves manufacturing throughput while simplifying the overall process.
Solution Approach 2:
The patent utilizes controllable laser parameters (power, pulse duration, wavelength, scan speed) to precisely control the ablation process. By adjusting these parameters, the system can remove material at controlled rates and patterns, enabling high-speed manufacturing without sacrificing precision. The ability to dynamically change laser parameters allows optimization for both throughput and manufacturing ease.
2Productivity
If emitter regions are densely packed to increase efficiency, then solar cell efficiency improves, but carrier recombination increases
Solution Approach 1:
The patent creates emitters with non-uniform doping profiles through controlled laser ablation. The doping concentration varies locally within each emitter region, with higher concentrations at specific locations and lower concentrations elsewhere. This local quality variation allows dense packing of emitters while maintaining low recombination losses in critical areas, as the doping profile is optimized for each local position rather than being uniform throughout.
Solution Approach 2:
The patent divides each emitter region into distinct zones with different doping characteristics. Through selective laser ablation and doping, each emitter is segmented into regions with optimized properties - some areas have high doping for electrical contact while other areas have lower doping to reduce recombination. This segmentation allows the emitter to simultaneously achieve high efficiency through dense packing while minimizing carrier recombination through localized property optimization.
3Ease of manufacture
If uniform emitter layout is used for both P-type and N-type regions, then fabrication process is simpler, but breakdown performance is reduced
Solution Approach 1:
The patent implements asymmetric layouts for P-type and N-type emitter regions. Rather than using identical patterns for both types, the system employs different geometries, spacing, and distributions optimized for each polarity's specific electrical characteristics. This asymmetry enables each emitter type to achieve optimal breakdown voltage performance while the overall fabrication process remains relatively simple through automated laser processing.
Solution Approach 2:
The patent applies different doping concentrations, geometries, and spatial distributions to P-type and N-type emitter regions based on their specific requirements. Each region type receives a customized layout optimized for its electrical properties, with local variations in doping profiles and geometric parameters. This localized optimization improves breakdown performance while the systematic approach maintains fabrication simplicity through consistent processing methods.
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 enhances solar cell efficiency by reducing carrier recombination, improving breakdown voltage, and simplifying the fabrication process, leading to higher power output and lower power losses compared to traditional solar cell architectures.
Implementation Method 1
performing laser ablating to form an opening in the amorphous silicon layer and the boron-doped silica glass layer
Implementation Method 2
dope a region of the N+ polycrystalline silicon layer
Implementation Method 3
etching to remove the exposed outer unmodified regions of the N+ polycrystalline silicon layer
Data Source
AI summary
Methods of fabricating solar cell emitter regions with differentiated P-type and N-type layouts and incorporating dotted diffusion, and resulting solar cells, are described. In an example, a solar cell includes a substrate having a light-receiving surface and a back surface. A first polycrystalline silicon emitter region of a first conductivity type is on a first thin dielectric layer on the back surface of the substrate. A second polycrystalline silicon emitter region of a second, different, conductivity type is on a second thin dielectric layer on the back surface of the substrate. The second polycrystalline silicon emitter region has a vertical thickness less than a vertical thickness of the first polycrystalline silicon emitter region.