Full-Laser Scribing for Flexible CIGS Solar Cells
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Solution Overview
Problem
The existing methods for manufacturing flexible stainless steel substrate CIGS thin-film solar cells face high efficiency loss and high production costs due to the screen printing process, which results in a significant dead zone and poor process reproducibility, and the full-laser scribing method on rigid substrates is not applicable due to the conductive nature of stainless steel.
Innovation Solution
A full-laser scribing method is employed on a flexible stainless steel substrate, where an insulating layer is sputtered to isolate the Mo layer, and three scribed lines are used to connect sub-cells without damaging the insulating layer, reducing the dead zone and power loss, and utilizing lasers with high repetition frequency for efficient processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If screen printing method is used to lead current out, then the manufacturing process is established, but the dead zone area increases to 7% of entire cell and efficiency loss is very high
Solution Approach 1:
The patent replaces the mechanical screen printing process with a laser-based scribing method. The laser writing device uses optical fields to directly scribe conductive patterns through the solar cell layers, eliminating the need for screen printing masks and paste deposition, thereby reducing dead zone area and improving efficiency while maintaining manufacturability
Solution Approach 2:
The patent changes the processing parameters by using laser energy density, pulse duration, and scanning speed to control the scribing depth and width. By adjusting these parameters, the method achieves precise conductive path formation with minimal dead zone impact, transforming the manufacturing approach from material deposition to energy-based material modification
2Ease of manufacture
If screen printing process is used, then current leading is achieved, but the process complexity increases and process reproducibility is poor
Solution Approach 1:
The patent replaces the complex mechanical screen printing system with a laser writing system that uses computer-controlled optical fields. This substitution eliminates mask alignment, paste viscosity control, and drying processes, simplifying the manufacturing process while improving reproducibility through digital parameter control
Solution Approach 2:
The laser writing device performs multiple functions: it creates conductive paths, defines active areas, and patterns electrodes all in a single process step. This multi-functionality replaces multiple sequential steps in screen printing, reducing process complexity and improving consistency
3Ease of manufacture
If screen printing method is used, then current leading is achieved, but silver paste consumption is high and production cost increases
Solution Approach 1:
The patent replaces silver paste deposition with laser-induced material removal or modification. The laser writing process uses optical energy to create conductive paths by removing insulating layers or modifying existing conductive layers, eliminating the need for expensive silver paste materials while maintaining electrical conductivity
Solution Approach 2:
The method discards the consumable silver paste material in favor of a non-consumable laser field. The laser system can be reused indefinitely without material depletion, transforming the production cost structure from high material consumption to low material consumption with higher equipment investment
4Productivity
If rigid substrate full-laser scribing method is used on flexible stainless steel substrate, then inner series connection is achieved, but the Mo layer is scribed off and insulating between cells cannot be formed
Solution Approach 1:
The patent applies different scribing strategies to different regions: in areas where Mo layer removal is undesirable, the laser parameters are adjusted to scribe only the upper layers while preserving the Mo layer. This local parameter adjustment ensures proper insulation where needed while maintaining conductivity where required, solving the contradiction between connection and insulation
Solution Approach 2:
The patent performs preliminary layer removal or modification before final scribing. By first creating a protective pattern or adjusting laser parameters, the method prevents unwanted Mo layer removal while ensuring proper insulation is achieved in subsequent scribing steps
5Productivity
If laser scribing is performed with high repetition frequency (30 MHz-1 GHz), then processing speed increases to 2-3 m/s, but the dead zone width must be reduced to 200 μm or less
Solution Approach 1:
The patent uses dynamic laser parameter adjustment during the scribing process. The laser repetition frequency, power, and scanning speed are dynamically coordinated to achieve the desired 200 μm or less dead zone width at high processing speeds of 2-3 m/s, allowing the system to adapt to different scribing requirements in real-time
Solution Approach 2:
The patent employs periodic laser pulsing at high repetition frequencies (30 MHz-1 GHz) to achieve precise material removal. The periodic nature of the laser pulses allows for controlled energy delivery, enabling narrow dead zone formation while maintaining high overall processing speed through rapid pulse sequencing
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 method significantly reduces the dead zone, power loss, and production costs, while ensuring high processing efficiency and low material consumption, with the added benefits of stable laser operation and long service life.
Implementation Method 1
using a laser to completely scribe off a molybdenum layer to form a first scribed line
Implementation Method 2
the laser is focused by a focusing lens and then is subjected to beam expansion by a beam expander, and then laser energy is shaped into a flat-topped distribution
Implementation Method 3
an insulating layer is sputtered to isolate the Mo layer
Data Source
AI summary
The invention relates a full-laser scribing method for a flexible stainless steel substrate solar cell module, comprising: preparing an insulating layer and a molybdenum layer on a stainless steel substrate in sequence; using a laser I to scribe the prepared insulating layer and molybdenum layer to form a first scribed line (P1); preparing the following film layers in sequence on the molybdenum layer in which P1 has been scribed: a CIGS layer, a cadmium sulfide layer and an intrinsic zinc oxide layer; using a laser II to make scribe and thus form a second scribed line (P2), wherein the second scribed line P2 is parallel with the first scribed line P1; and preparing an aluminum-doped zinc oxide layer on the intrinsic zinc oxide layer in which P2 has been scribed, and using a laser III to make scribe and thus form a third scribed line (P3), wherein the third scribed line P3 is parallel with the first scribed line P1. The invention may avoid disadvantages caused by the screen printing, such as large dead zone, expensive screen printing paste and frequent replacement of screens for screen printing, thereby improve efficiency and stability of the module and save cost and increase production efficiency.