Solar Cell Doped Layer Asymmetry for Passivation and Light Use
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Solution Overview
Problem
Existing solar cells have low photoelectric conversion efficiency due to excessive carrier recombination at the surface and uneven light receptivity between the front and rear surfaces, which is exacerbated by the diffusion process and differing doped conductive layers on each surface.
Innovation Solution
A solar cell design featuring a first doped conductive layer on the front surface and a second doped conductive layer on the rear surface, where the full width at half maximum of the first doped conductive layer is not greater than the second, optimizing crystallite size to reduce parasitic absorption and enhance passivation, thereby improving light utilization and carrier collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a doped conductive layer is formed over the substrate surface to enhance passivation effect, then carrier recombination is suppressed, but photoelectric conversion efficiency remains low due to parasitic absorption
Solution Approach 1:
The patent applies different doping types (first doping element vs. second doping element) and different crystallite sizes to the front and rear doped conductive layers respectively. The front surface layer has smaller crystallite size for better passivation, while the rear surface layer has larger crystallite size for reduced parasitic absorption,实现ing local optimization of different surface requirements
Solution Approach 2:
The patent creates asymmetric structure by forming doped conductive layers with different properties on the front and rear surfaces of the substrate. The front surface doped layer has different doping element type and crystallite size compared to the rear surface doped layer, breaking the symmetry to optimize各自 surface functions
2Loss of energy
If the full width at half maximum of the first doped conductive layer is reduced to increase crystallite size, then parasitic absorption decreases, but passivation effect may be compromised
Solution Approach 1:
The patent optimizes crystallite size locally for each surface: the front surface doped layer maintains smaller crystallite size (narrower FWHM) for strong passivation effect, while the rear surface doped layer has larger crystallite size (wider FWHM) to reduce parasitic absorption of light, achieving local quality optimization
Solution Approach 2:
The patent changes the crystallite size parameter (controlled by FWHM of Raman spectrum peak) differently for front and rear doped layers. By controlling the FWHM values to satisfy FWHM1 ≤ FWHM2, the patent adjusts the crystallite size parameter to balance passivation and light absorption requirements
3Reliability
If different doping elements are used on front and rear surfaces to optimize band bending, then field passivation is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies different doping element types locally: first doping element (e.g., phosphorus for N-type) on the front surface and second doping element (e.g., boron for P-type) on the rear surface. This local differentiation enhances field passivation by creating appropriate band bending at each surface while maintaining overall process feasibility
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 design enhances the photoelectric conversion performance by reducing carrier recombination and increasing open-circuit voltage and short-circuit current while maintaining high light utilization, leading to improved overall efficiency.
Implementation Method 1
Solar cells have good photoelectric conversion capabilities
Implementation Method 2
The doped conductive layer is used for field passivation
Implementation Method 3
the doping element in the doped conductive layer can be used for band bending at the surface of the substrate
Implementation Method 4
a full width at half maximum near a first peak of a Raman spectrum for the first doped conductive layer is not greater than a full width at half maximum near a first peak of a Raman spectrum for the second doped conductive layer
Data Source
AI summary
Embodiments of the present disclosure relates to the field of solar cells, and in particular to a solar cell and a photovoltaic module. The solar cell includes: a substrate having a front surface and a rear surface; a first tunnel layer and a first doped conductive layer sequentially formed over the front surface of the substrate, the first tunnel layer and the first doped conductive layer are each aligned with a metal pattern region on the front surface; and a second tunnel layer and a second doped conductive layer sequentially formed over the rear surface of the substrate, and in a respective Raman spectrum, a full width at half maximum corresponding to the first doped conductive layer is not greater than a full width at half maximum corresponding to the second doped conductive layer.