Back-Contact Solar Cell Rear Laser Patterning Without Photolithography
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Solution Overview
Problem
Conventional crystalline silicon solar cells face efficiency limitations due to shadowing from front electrodes, and their fabrication process is complicated and costly due to the need for photolithography in forming rear electrodes.
Innovation Solution
A laser-based method is used to form patterns for p-type and n-type semiconductor regions on the rear surface of a back contact solar cell, eliminating the need for photolithography and simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography is used to form patterns for p-type and n-type semiconductor regions on the rear surface, then manufacturing precision is improved, but device complexity and fabrication cost increase
Solution Approach 1:
The patent replaces the photolithography process (which uses light and chemical processes) with a direct laser writing method. The laser beam is directly scanned on the rear surface to form patterns for p-type and n-type semiconductor regions, eliminating the need for photoresist coating, exposure, and development steps. This substitution maintains manufacturing precision while significantly reducing fabrication process complexity.
Solution Approach 2:
The patent extracts and removes the photolithography step from the fabrication process. By using direct laser writing to form the patterns, the complex multi-step photolithography process (including photoresist application, exposure, and development) is completely eliminated, leaving only the essential pattern formation and semiconductor region creation steps.
2Manufacturing precision
If photolithography is used to form patterns for p-type and n-type semiconductor regions on the rear surface, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The patent replaces the time-consuming photolithography process with direct laser writing. The laser beam can be rapidly scanned and focused to form patterns directly, eliminating the sequential steps of photoresist coating, exposure, and development that are inherent in photolithography. This substitution maintains pattern formation precision while dramatically reducing the total fabrication time.
Solution Approach 2:
The laser writing process allows for direct pattern formation without requiring preliminary photoresist coating and alignment steps. The pattern is formed directly by the laser beam scanning, which can be pre-programmed with the exact pattern coordinates, eliminating the need for separate photoresist application and exposure alignment steps that consume time in photolithography.
3Ease of operation
If front electrodes are formed on the light-receiving face to enable electrical contact, then ease of operation is improved, but shadowing occurs reducing efficiency
Solution Approach 1:
The patent inverts the conventional electrode placement approach by moving all electrical contact structures to the rear surface of the solar cell instead of the front light-receiving face. The rear surface patterns form p-type and n-type semiconductor regions that provide electrical contact, completely eliminating front electrodes. This inversion resolves the shadowing problem while maintaining ease of operation for electrical contact.
Solution Approach 2:
The patent transitions the electrical contact structures from the two-dimensional front surface to the rear surface, effectively using another dimension (the rear surface plane) to achieve the same electrical contact function. This dimensional relocation eliminates the shadowing effect on the light-receiving face while preserving the electrical contact capability through the formed semiconductor regions.
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 efficiency by minimizing shadowing and reducing electron-hole pair recombination while lowering fabrication costs and time.
Implementation Method 1
removing the oxide layer by irradiating laser light to the oxide layer formed on the rear surface of the substrate at predetermined intervals to form a pattern of the different conductive type semiconductor regions
Implementation Method 2
The solar cell, which is a device converting light energy into electrical energy using a photovoltaic effect
Data Source
AI summary
The present invention discloses a back contact solar cell. The back contact solar cell includes a semiconductor substrate having a front surface and a rear surface; a first conductive type semiconductor region having a first conductive type and a second conductive type semiconductor region having a second conductive type at an interval on the rear surface of the semiconductor substrate. Furthermore, the rear surface of the semiconductor substrate has a texturing structure at the interval between the first conductive type semiconductor region and the second conductive type semiconductor region.