Textured Back-Contact Solar Cell Passivation for Light Trapping
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Solution Overview
Problem
Current solar cells face inefficiencies in photoelectric conversion due to issues in the preparation of back contact passivation structures, particularly with technologies like Low Pressure Chemical Vapor Deposition (LPCVD), which affect the overall performance of the cell.
Innovation Solution
The solar cell design incorporates a substrate with textured structures and corresponding holes in the doped semiconductor layer, filled by a passivation layer, which enhances internal reflection and light trapping, while providing simultaneous passivation, thereby improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LPCVD is used to prepare the tunneling oxide layer and polysilicon layer, then manufacturing cost is reduced and yield is improved, but photoelectric conversion efficiency is affected due to process limitations
Solution Approach 1:
The patent changes the fundamental preparation method parameters from chemical vapor deposition to physical sputtering, altering the deposition mechanism to achieve better film quality and interface characteristics that improve photoelectric conversion while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces the chemical deposition process (CVD) with a physical sputtering process, substituting chemical reactions with physical momentum transfer to form the tunneling oxide and polysilicon layers, thereby eliminating chemical process limitations
2Ease of manufacture
If a conventional flat surface structure is used, then manufacturing is simpler, but light absorption is insufficient leading to reduced efficiency
Solution Approach 1:
The patent introduces curved and textured surface structures including random textures, ordered pyramids, and inverted pyramids on the substrate surface, replacing flat surfaces to enhance light trapping and absorption through multiple internal reflections
Solution Approach 2:
The patent adds vertical dimensionality to the surface structure by creating multi-level pyramidal textures and inverted pyramids, transforming a two-dimensional flat surface into a three-dimensional structured surface to increase light interaction path length
3Reliability
If the doped semiconductor layer is made continuous without holes, then electrical conductivity is improved, but light trapping capability is reduced
Solution Approach 1:
The patent applies local quality by creating selective holes in specific regions of the doped semiconductor layer while maintaining material continuity in other areas, allowing simultaneous optimization of light trapping in hole regions and electrical conductivity in continuous regions
Solution Approach 2:
The patent segments the continuous doped semiconductor layer by introducing periodic hole structures, dividing it into multiple regions that can independently optimize for both light absorption and electrical transport functions
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
The proposed structure increases short circuit current and open circuit voltage, enhancing the photoelectric conversion efficiency of the solar cell by reducing light loss and surface defects.
Implementation Method 1
The textured structures can improve internal reflection of the substrate, thereby reducing light loss of the solar cell
Implementation Method 2
The solar cell generates carriers by using a photovoltaic effect principle and introduces the carriers out by using an electrode
Implementation Method 3
a chemical passivation of the tunneling oxide layer and a field passivation of the polysilicon layer may be utilized to significantly reduce a recombination rate of minority carriers
Implementation Method 4
a chemical passivation of the tunneling oxide layer and a field passivation of the polysilicon layer may be utilized
Data Source
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AI summary
Disclosed are a solar cell, a tandem solar cell, and a photovoltaic module. The solar cell includes a substrate, a doped semiconductor layer, a passivation layer and a plurality of electrodes. The substrate is provided with textured structures on a portion of a surface of the substrate. The doped semiconductor layer is disposed on the substrate. The solar cell further includes holes extending through the doped semiconductor layer, and corresponding, respectively, to the textured structures, and a bottom of a respective hole exposes at least a portion of a corresponding textured structure. The passivation layer is formed over a surface of the doped semiconductor layer away from the substrate, fills the holes. The plurality of electrodes are arranged along a first direction, pass through the passivation layer and are in electrical contact with the doped semiconductor layer.