Solar Cell Doping Structure for Passivation and Carrier Transport
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Solution Overview
Problem
Existing solar cells face challenges in improving passivation performance in the metallization region, which limits the conversion efficiency and makes mass production difficult.
Innovation Solution
A solar cell design that includes a semiconductor substrate with a first and second surface, an emitter, passivation layers, a tunneling layer, doped conductive layers, and a retardation layer. The first doped conductive layer with a low concentration is located in the metallization region, while the second doped conductive layer with a higher concentration covers the entire second surface, including the non-metallization region. The retardation layer retards the migration of doped elements, improving passivation and carrier transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a doped conductive layer is formed in the metallization region to improve carrier collection, then the lateral transport capability of carriers is improved, but the passivation performance deteriorates due to increased recombination loss
Solution Approach 1:
The doped conductive layer is segmented into multiple layers with different doping concentrations: a first doped conductive layer with lower doping concentration adjacent to the tunneling layer, and a second doped conductive layer with higher doping concentration further from the tunneling layer. This segmentation allows the first layer to maintain passivation performance while the second layer provides sufficient carrier collection capability.
Solution Approach 2:
Different regions of the doped conductive layer structure have different local properties: the first doped conductive layer has lower doping concentration to preserve passivation near the tunneling layer, while the second doped conductive layer has higher doping concentration to ensure lateral transport in the metallization region. This local quality variation resolves the contradiction between passivation and carrier collection.
2Speed
If the doping concentration is increased to improve lateral transport capability, then carrier transport efficiency is improved, but passivation performance deteriorates due to increased recombination
Solution Approach 1:
The doped conductive layer is divided into segments with different doping concentrations. The first segment (first doped conductive layer) has lower doping concentration to minimize recombination loss and maintain passivation, while the second segment (second doped conductive layer) has higher doping concentration to provide sufficient lateral transport capability.
Solution Approach 2:
The structure implements local quality variation by having different doping concentrations at different positions within the doped conductive layer. The lower doping concentration region is positioned where passivation is critical, while the higher doping concentration region is positioned where lateral transport is needed, thus resolving the contradiction between transport speed and energy loss.
3Loss of energy
If passivation is enhanced to reduce recombination loss, then conversion efficiency is improved, but carrier transport capability deteriorates
Solution Approach 1:
The doped conductive layer structure is segmented into two layers with different doping concentrations. The first doped conductive layer with lower doping concentration provides good passivation and reduces recombination loss, while the second doped conductive layer with higher doping concentration ensures sufficient carrier transport capability to the metallization region.
Solution Approach 2:
Different local regions of the doped conductive layer structure have different properties optimized for their specific functions: the first doped conductive layer has lower doping concentration to minimize recombination loss and enhance passivation, while the second doped conductive layer has higher doping concentration to ensure carrier transport capability, thus resolving the contradiction between passivation and transport.
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 passivation effect in the metallization region and ensures efficient lateral transport of carriers, thereby improving the photoelectric conversion efficiency of the solar cell.
Implementation Method 1
a tunneling layer formed over the second surface of the semiconductor substrate; a first doped conductive layer and a retardation layer formed on a surface of the tunneling layer
Implementation Method 2
a first doped conductive layer and a retardation layer formed on a surface of the tunneling layer, the first doped conductive layer is located between the tunneling layer and the retardation layer
Implementation Method 3
the retardation layer is configured to retard migration of a doped element in the second doped conductive layer to the first doped conductive layer
Data Source
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AI summary
A solar cell, a manufacturing method thereof, and a photovoltaic module. The solar cell includes: a semiconductor substrate including first and second surfaces opposite to each other; emitter and first passivation layer formed over the first surface; tunneling layer formed over the second surface; first doped conductive layer and retardation layer formed on the tunneling layer and corresponding to metallization region, the first doped conductive layer is located between the tunneling layer and the retardation layer; second doped conductive layer formed over the tunneling layer and covering the tunneling layer in non-metallization region and the retardation layer, the retardation layer is configured to retard migration of doped element in the second doped conductive layer to the first doped conductive layer; second passivation layer formed over the second doped conductive layer; and second electrode forming contact with the second doped conductive layer and first electrode forming contact with the emitter.