Backside Contact Solar Cell Trench Isolation for Recombination Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polysilicon doped regions in solar cells experience high recombination in the space charge region where they touch, leading to reduced efficiency due to low charge carrier lifetime.
Innovation Solution
A trench structure separates the P-type and N-type doped regions, preventing physical contact and incorporating a textured surface and a dielectric layer with positive fixed charge density to improve surface passivation and solar radiation collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If P-type and N-type doped regions are placed in direct contact on the backside, then device complexity is reduced, but recombination losses increase due to space charge region formation
Solution Approach 1:
The patent introduces a trench structure that segments the backside contact surface, physically separating the P-type and N-type doped regions. This segmentation prevents direct contact between opposite polarity regions, eliminating the harmful space charge region and associated recombination losses while maintaining electrical functionality through separate contact paths.
Solution Approach 2:
The trench acts as an intermediary barrier between the P-type and N-type doped regions. By introducing this intermediate structure, the patent prevents direct interaction between the doped regions that would otherwise create a space charge region, thereby reducing recombination without requiring complex additional components.
2Loss of energy
If a trench structure is introduced to separate doped regions, then recombination losses are reduced, but device complexity increases
Solution Approach 1:
The trench structure segments the backside surface into distinct regions for P-type and N-type contacts. This simple geometric division effectively reduces recombination losses by preventing space charge region formation, while the segmentation itself is achieved through straightforward fabrication processes that minimize added complexity.
3Loss of energy
If doped regions are separated by a trench, then recombination is prevented, but manufacturing precision requirements increase
Solution Approach 1:
The trench provides a clear geometric boundary that segments the contact regions. While this requires precise formation, the segmented structure tolerates reasonable variations in trench dimensions as long as complete separation is achieved, making the precision requirements manageable through standard fabrication techniques.
4Area of stationary object
If backside contact configuration is used, then front surface area is maximized for light collection, but charge carrier lifetime is reduced due to recombination at contact regions
Solution Approach 1:
By segmenting the backside contact structure with a trench, the patent prevents the formation of a continuous space charge region that would reduce carrier lifetime. This allows the front surface to be fully utilized for light collection while the segmented backside maintains electrical functionality without harmful recombination effects.
Solution Approach 2:
The trench serves as an intermediary structure that eliminates the harmful interaction between P-type and N-type regions. This mediator prevents charge carrier recombination at the contact regions, thereby preserving charge carrier lifetime while allowing the backside contact configuration to maximize front surface area for photovoltaic conversion.
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 trench structure increases solar cell efficiency by preventing recombination, enhancing surface passivation, and improving solar radiation collection, resulting in improved power generation capabilities.
Implementation Method 1
The trench structure may include a textured surface for increased solar radiation collection
Implementation Method 2
incorporating a textured surface and a dielectric layer with positive fixed charge density to improve surface passivation
Data Source
AI summary
A solar cell includes polysilicon P-type and N-type doped regions on a backside of a substrate, such as a silicon wafer. A trench structure separates the P-type doped region from the N-type doped region. Each of the P-type and N-type doped regions may be formed over a thin dielectric layer. The trench structure may include a textured surface for increased solar radiation collection. Among other advantages, the resulting structure increases efficiency by providing isolation between adjacent P-type and N-type doped regions, thereby preventing recombination in a space charge region where the doped regions would have touched.