Rear-Face Interdigitated Contact PV Cell Laser Doping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing process of photovoltaic cells with interdigitated contacts on the rear face is complex and expensive, making them less competitive compared to less efficient but more affordable homojunction cells.
Innovation Solution
A method involving selective irradiation of a doped silicon substrate with a luminous flux to form doped regions and electrically insulating regions, allowing for the creation of interdigital contacts on the rear face with reduced complexity and cost, using techniques like laser doping and PECVD deposition of silicon nitride layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to form interdigitated p+ and n+ regions on the rear face, then high efficiency is achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent combines the formation of p+ and n+ regions into a single diffusion step by applying a combined doping layer containing both phosphorus and boron dopants. The selective laser irradiation activates dopants in specific patterns to form interdigitated regions, merging multiple fabrication steps into one unified process that reduces complexity while maintaining efficiency
Solution Approach 2:
The doping layers containing phosphorus and boron are deposited in advance on the rear face before the diffusion activation step. This preliminary preparation allows the subsequent laser irradiation to selectively activate dopants in predetermined patterns, simplifying the overall manufacturing process by pre-positioning all necessary dopant materials
2Manufacturing precision
If multiple deposition and etching steps are performed to form doped regions, then precise doping patterns are achieved, but manufacturing cost and process time increase
Solution Approach 1:
The patent replaces traditional mechanical photolithography and etching processes with selective laser irradiation. The laser directly activates dopant diffusion in precise patterns without requiring photoresist deposition, patterning, or etching steps, thereby achieving high precision doping patterns while dramatically reducing manufacturing cycle time
Solution Approach 2:
The patent uses selective laser irradiation with controlled fluence parameters to activate dopant diffusion only in specific regions. By adjusting laser parameters (fluence, pulse duration, scanning speed), precise doping patterns are achieved in a single step, eliminating multiple processing steps and reducing overall manufacturing time
3Reliability
If electrically insulating regions are formed by laser ablation or additional deposition and etching, then proper electrical insulation is achieved, but process complexity increases
Solution Approach 1:
The patent combines the formation of electrically insulating regions with the doping pattern formation in the same selective laser irradiation step. By controlling laser fluence and exposure, regions with balanced dopant concentrations (p+ and n+ dopants canceling each other) are created, providing electrical insulation without requiring separate ablation or deposition-etching steps
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 simplifies and reduces the cost of producing photovoltaic cells with interdigitated contacts, potentially increasing their market share by achieving efficient doping and insulation without the need for additional deposition and etching steps.
Implementation Method 1
selective irradiation of a region of the doping layer by a luminous flux which causes the diffusion of the dopants of the irradiated region of the dopant layer into the underlying region of the semiconductor layer doped
Implementation Method 2
selective irradiation of at least one region of the doping layer by a light flux whose fluence is within a range called the 'doping compensation range' for which the dopants of the irradiated region of the doping layer diffuse into the underlying region of the doped semiconductor layer so as to balance the concentrations of the two species of dopants
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
The invention concerns a method for producing a photovoltaic cell with interdigitated contacts in the rear face, comprising: - providing a doped silicon substrate (1), - forming, on the rear face (B) of said substrate (1), a doped semiconductor layer (10) with a first dopant species, - forming, on said layer (10), a dopant layer (11) comprising a second dopant species, of an electric type opposite to that of the first species (10), - forming, in the doped layer (10), at least one doped region (10a) of a type opposite to that of the first species, by irradiation of at least one region (11a) of the dopant layer (11) with a luminous flux of fluence greater than a threshold above which the dopants of the irradiated region (11a) of the dopant layer (11) diffuse into the region (10a) underlying the doped layer (10) in such a way as to exceed the concentration of the first dopant species, - forming, in the doped layer (10), at least one electrically insulating region (10b), by selective irradiation of at least one region (11b) of the dopant layer (11) with a luminous flux of which the fluence is in a range ([S1-S2]) lower than said threshold, at which the dopants of the irradiated region (11b) of the dopant layer (11) diffuse into the region (10b) underlying the doped semiconductor layer (10) in such a way as to balance the concentrations of the two dopant species in said region (10b).