Solar Cell Back-Edge Isolation Using Insulating Passivation Layers
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Solution Overview
Problem
The existing HJT solar cell design results in incomplete coverage of the back transparent conductive oxide layer at the cell edge, leading to poor passivation and increased vulnerability to sodium ions and water vapor ingress, which decreases cell efficiency and reliability.
Innovation Solution
A solar cell design incorporating a first and second transparent conductive oxide layer separated by an insulating passivation layer, with the second electrode extending through the passivation layer to maintain electrical connection, and a method for forming these layers to ensure complete coverage and prevent electrical conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mask plate is disposed at the edge of the P-type doped amorphous silicon layer to prevent electrical conduction between front and back surfaces, then electrical leakage is avoided, but the back transparent conductive oxide layer coverage becomes incomplete at the cell edge
Solution Approach 1:
An insulating passivation layer is introduced as an intermediary component between the front and back transparent conductive oxide layers at the cell edge. This passivation layer serves as a mediator that provides both electrical isolation (preventing leakage) and complete area coverage (eliminating the blank region), thereby resolving the contradiction between reliability and coverage area.
2Reliability
If the back transparent conductive oxide layer is coated with incomplete coverage at the edge, then electrical conduction between surfaces is prevented, but sodium ions and water vapor can easily invade the cell
Solution Approach 1:
The solution employs a composite structure combining the insulating passivation layer with the transparent conductive oxide layers. The passivation layer material (such as silicon nitride or silicon oxide) provides superior barrier properties against sodium ions and water vapor while maintaining electrical isolation, thus resolving the contradiction between preventing electrical conduction and blocking harmful factor ingress.
3Reliability
If the back transparent conductive oxide layer has incomplete coverage, then electrical isolation is achieved, but the passivation effect deteriorates and cell efficiency is lost
Solution Approach 1:
The edge region of the solar cell is segmented into distinct functional zones: the insulating passivation layer provides electrical isolation and environmental protection, while the transparent conductive oxide layers maintain optical and electrical functionality in the active regions. This segmentation allows each component to perform its specific function optimally, resolving the contradiction between electrical isolation and passivation effect.
Data Source
AI summary
A solar cell, comprising a silicon cell main body (110), a first transparent conductive oxide layer (120), a second transparent conductive oxide layer (130), an insulating passivation layer (160), and a second electrode (150), wherein the insulating passivation layer (160) covers edges of the back face of the silicon cell main body (110), and at the edges of the back face of the silicon cell main body (110), the second transparent conductive oxide layer (130) and the first transparent conductive oxide layer (120) are arranged spaced apart from each other by means of the insulating passivation layer (160) arranged therebetween.