IBC Solar Cell Backside Texture Layout for Carrier Transport
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Solution Overview
Problem
The challenge is to enhance the efficiency of Interdigitated Back Contact (IBC) solar cells without altering the ratio of p+ to n+ at the back surface, which affects the pitch width and minority carrier transport, thereby limiting their performance.
Innovation Solution
The solution involves a solar cell design with staggered first and second regions on the back surface, separated by gap regions, featuring a first and second conductive layer with opposite conductivity types, pyramidal texture structures, and a curved interface region between the conductive layers and gap regions, along with passivation layers to improve light trapping and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pitch width at the back surface is reduced to increase contact area, then the photoelectric conversion efficiency is improved, but the minority carrier transport is hindered
Solution Approach 1:
The back surface is divided into first regions with first conductive type and second regions with second conductive type, arranged in an interdigitated pattern. This segmentation allows separate optimization of contact area and carrier transport paths, resolving the contradiction between increased contact area and maintained carrier transport efficiency
Solution Approach 2:
Different regions of the back surface are assigned different conductivity types (first conductive type in first regions, second conductive type in second regions) to create locally optimized conditions for both carrier collection and transport, enabling simultaneous improvement of efficiency and reliability
2Reliability
If the pitch width at the back surface is increased to improve minority carrier transport, then the carrier transport is enhanced, but the contact area is reduced
Solution Approach 1:
The back surface is segmented into alternating first regions and second regions with different conductivity types, allowing the structure to simultaneously achieve sufficient contact area through multiple contact regions and adequate pitch width for carrier transport between regions
Solution Approach 2:
The interdigitated arrangement of first and second regions creates a two-dimensional optimization where both contact area and pitch width are optimized simultaneously by utilizing the spatial distribution of different conductivity types across the back surface
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 light absorption and reflection, increasing the photoelectric conversion efficiency of IBC solar cells by optimizing the structure and contact areas, while maintaining the original ratio of p+ to n+ at the back surface.
Implementation Method 1
This design enhances light absorption and reflection
Implementation Method 2
first pyramidal texture structures formed on the back surface corresponding to the gap regions
Implementation Method 3
A curved interface region is formed between a side wall of the first conductive layer and/or the second conductive layer and a side wall of the gap region adjacent thereto
Implementation Method 4
An Interdigitated Back Contact (IBC) solar cell has a light receiving surface with no electrode arranged thereon, while positive and negative electrodes are arranged in an interdigitated manner on a backlight surface of the solar cell
Data Source
Figure 1-1~1-2
Figure 1-3~3
Figure 4~7
AI summary
A solar cell includes: a substrate having front and back surfaces opposite to each other, the back surface includes first regions, second regions and gap regions, the first regions and the second regions are staggered and spaced from each other in a first direction, and each gap region is provided between one first region and one adjacent second region; a first conductive layer formed over the first region; a second conductive layer formed over the second region, the second conductive layer has a conductivity type opposite to the first conductive layer; a first electrode forming electrical contact with the first conductive layer; a second electrode forming electrical contact with the second conductive layer; and first pyramidal texture structures formed on the back surface corresponding to the gap regions. A curved interface region is formed between side wall of the first/second conductive layer and side wall of the adjacent gap region.