Solar Cell Impurity Region Formation via Laser Irradiation
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Solution Overview
Problem
Current solar cell manufacturing methods face challenges in efficiently forming impurity regions with varying impurity concentrations and depths, which affects the solar cell's efficiency and performance.
Innovation Solution
A method involving the formation of impurity layers on a substrate using techniques like screen printing, sputtering, ink jetting, or spin-on coating, followed by laser irradiation to create regions with different impurity concentrations and depths, allowing for the formation of high-doped emitter and back surface field portions, thereby optimizing the p-n junction and improving charge collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional thermal diffusion method is used to form impurity regions, then the manufacturing process is simple, but the impurity concentration distribution and depth control are insufficient
Solution Approach 1:
The impurity region formation is divided into multiple stages: first forming a base impurity region through thermal diffusion, then creating high-doped portions through selective laser irradiation. This segmentation allows different regions to have different impurity concentrations and depths, achieving precise control over the impurity profile while maintaining process simplicity.
Solution Approach 2:
The laser irradiation is applied in a periodic manner to selectively enhance impurity doping in specific regions. By controlling the laser pulse duration, frequency, and spatial distribution, the method achieves precise control over impurity concentration profiles without requiring complex continuous processing equipment.
2Reliability
If uniform impurity doping is applied across the entire emitter region, then the manufacturing process is simple, but the charge collection efficiency and carrier lifetime are reduced due to recombination
Solution Approach 1:
The emitter region is designed with non-uniform impurity distribution: high-doped portions are created only in specific locations where electrodes contact the emitter, while other regions maintain lower impurity concentrations. This local quality differentiation reduces recombination losses in low-doped areas, extending carrier lifetime, while ensuring good electrical contact in high-doped electrode contact regions.
Solution Approach 2:
The impurity concentration parameter is varied spatially across the emitter region. By controlling laser irradiation parameters (intensity, duration, position), the method creates regions with different impurity concentrations optimized for different functions: high concentration for electrical contact and low concentration for charge collection and carrier lifetime extension.
3Object-affected harmful factors
If high impurity concentration is used throughout the emitter region to improve electrical contact, then the contact resistance is reduced, but the recombination loss increases and power conversion efficiency decreases
Solution Approach 1:
High impurity concentration is localized only to the electrode contact portions of the emitter region, where low contact resistance is critical. The remaining emitter region maintains lower impurity concentration, minimizing recombination losses and maximizing power conversion efficiency. This spatial differentiation of impurity concentration optimizes both electrical contact and energy conversion performance.
Solution Approach 2:
The emitter region is segmented into functionally distinct zones: high-doped electrode contact regions for minimizing contact resistance and low-doped active regions for maximizing charge collection efficiency. The selective laser irradiation method enables precise creation of these segmented regions with appropriate impurity concentrations for each function.
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 the solar cell's efficiency by improving charge collection and reducing recombination, leading to increased power conversion efficiency and prolonged carrier lifetime.
Implementation Method 1
diffusing the impurities into the substrate by irradiating laser beams on the impurity layer
Implementation Method 2
diffusing the impurities into the substrate by irradiating laser beams on the impurity layer
Implementation Method 3
The electron-hole pairs are separated into electrons and holes by the photovoltaic effect
Data Source
AI summary
Disclosed is a method for manufacturing a solar cell. The method includes forming an impurity layer on a substrate of a first conductive type, the impurity layer having impurities of a second conductive type opposite the first conductive type; forming a first emitter portion having a first impurity concentration in the substrate using the impurity layer by heating the substrate with the impurity layer; forming a second emitter portion having a second impurity concentration at the first emitter portion using the impurity layer by irradiating laser beams on a region of the impurity layer, the second impurity concentration being greater than the first impurity concentration; and forming a first electrode connected to the second emitter portion and a second electrode connected to the substrate.