Passivated Solar Cell Contact Structure for Lower Recombination Loss
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Solution Overview
Problem
The conversion efficiency of existing solar cells is limited by recombination losses at metal contact areas, and existing passivated contact cells, such as HIT and TOPCon cells, require further improvement.
Innovation Solution
A solar cell design incorporating a substrate with an interface passivation layer, a field passivation layer, and a conductive enhancement layer, where the conductive enhancement layer has a lower resistivity than the field passivation layer, allowing carriers to flow directly to the electrode with reduced series resistance and increased efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a passivated contact is used to reduce recombination losses, then conversion efficiency is improved, but series resistance increases and carrier transmission is hindered
Solution Approach 1:
The patent divides the passivation layer into two distinct sub-layers with different functions: the first interface passivation sub-layer provides field passivation to reduce recombination losses, while the second interface passivation sub-layer incorporates a conductive enhancement layer to improve carrier transmission. This local differentiation of properties resolves the contradiction between reducing recombination and maintaining low series resistance.
Solution Approach 2:
The patent uses a composite structure combining the field passivation layer with a conductive enhancement layer having lower resistivity (less than 0.001 Ω·cm). This composite material approach allows the system to simultaneously achieve effective field passivation and low series resistance, resolving the contradiction between energy loss reduction and carrier transmission reliability.
2Loss of energy
If the field passivation layer is made thicker to improve passivation effect, then recombination loss is reduced, but carrier transmission path length increases and resistance increases
Solution Approach 1:
The patent creates a localized conductive path through the conductive enhancement layer positioned at the interface between the passivation layer and the electrode. This allows carriers to bypass the thicker field passivation layer through a low-resistance path, thus reducing both recombination loss and transmission path length simultaneously.
Solution Approach 2:
The conductive enhancement layer acts as an intermediary that facilitates carrier transport between the field passivation layer and the electrode. It provides a low-resistance bridge that shortens the effective carrier transmission path while maintaining the thickness of the field passivation layer needed for effective passivation.
3Loss of energy
If more passivation layers are added to reduce recombination, then conversion efficiency is improved, but device complexity increases
Solution Approach 1:
The conductive enhancement layer serves multiple functions simultaneously: it reduces series resistance, provides an additional passivation interface, and creates a low-resistance carrier transport path. This multi-functionality allows the system to achieve effective passivation without proportionally increasing structural complexity.
Solution Approach 2:
Rather than uniformly increasing passivation throughout the structure, the patent locally enhances passivation quality at critical interfaces (substrate-passivation layer and passivation layer-electrode) through targeted sub-layers. This localized approach reduces recombination losses without requiring a proportional increase in overall layer complexity.
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 design enhances carrier transmission rates and reduces losses, leading to improved conversion efficiency while maintaining effective field passivation and minimizing surface recombination.
Implementation Method 1
a conductive enhancement layer, at least partially disposed at a side of the first interface passivation sub-layer facing away from the substrate, and configured to enable carriers in the first interface passivation sub-layer to flow to the at least one electrode
Implementation Method 2
the solar cell is usually passivated by a passivated contact in order to reduce the recombination therein and on the surface of the solar cell
Implementation Method 3
a field passivation layer, at least partially disposed between the interface passivation layer and the at least one electrode
Data Source
AI summary
The present disclosure provide a solar cell, including: a substrate, an interface passivation layer covering a rear surface of the substrate, and an electrode disposed at a side of the interface passivation layer facing away from the substrate, the interface passivation layer including a first interface passivation sub-layer corresponding to a portion of the interface passivation layer between adjacent electrodes and a second interface passivation sub-layer corresponding to a portion of the interface passivation layer where disposed between the substrate and the electrode; a field passivation layer, at least partially disposed between the interface passivation layer and the electrode; and a conductive enhancement layer, at least partially disposed at a side of the first interface passivation sub-layer away from the substrate to enable carriers in the first interface passivation sub-layer to flow to the electrode, where a resistivity of the conductive enhancement layer is smaller than a resistivity of the field passivation layer.