CIS Solar Cell Backside Electrode Intermediate Layer Shunt Resistance
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Solution Overview
Problem
CIS-based thin film solar cells face issues with leakage current due to shunt paths, which reduce conversion efficiency and require additional processing steps or special materials, and increasing the width of dividing grooves reduces energy generation area and efficiency.
Innovation Solution
A CIS-based thin film solar cell design with a backside electrode layer featuring an intermediate layer composed of a metal compound and a group VI element, where the film thickness of the lateral surface portion is at least twice that of the surface portion, reducing leakage current without additional processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating material is incorporated between adjacent regions of the backside electrode layer to reduce leakage current, then shunt resistance is improved, but device complexity and manufacturing cost increase due to additional processing steps
Solution Approach 1:
An intermediate layer composed of a compound containing a metal from the backside electrode layer and a group VI element from the light absorption layer is formed at the interface between the backside electrode layer and light absorption layer. This intermediate layer acts as a mediator that naturally reduces leakage current through the shunt path without requiring additional insulating materials or processing steps, thereby improving shunt resistance while maintaining simple device structure
Solution Approach 2:
The thickness of the intermediate layer is varied across different regions: the first intermediate layer portion on the upper surface has a different thickness than the second intermediate layer portion on the lateral surface. By changing the thickness parameter spatially, the structure optimizes both electrical performance (reducing leakage current) and optical performance (maintaining light absorption) without adding complex processing steps
2Reliability
If the width of pattern 1 is increased to reduce leakage current influence, then shunt resistance is improved, but the area for generating electric energy decreases, reducing conversion efficiency
Solution Approach 1:
The intermediate layer is formed with spatially varying thickness: a first intermediate layer portion on the upper surface and a second intermediate layer portion on the lateral surface with different thicknesses. This local quality variation allows the structure to provide enhanced leakage current blocking at critical interfaces while preserving maximum active area for light absorption and energy generation, thus improving shunt resistance without sacrificing conversion efficiency
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 shunt resistance and fill factor, improving solar cell efficiency while maintaining conventional fabrication processes and avoiding the need for special materials.
Implementation Method 1
a shunt path (20c) is formed through the light absorption layer between the adjacent regions of the backside electrode layer divided by pattern 1 (P1) and a leakage current flowing through the shunt path (20c) causes problems of reduction of conversion efficiency
Implementation Method 2
CIS-based thin film solar cell having an integrated structure, in which a backside electrode layer formed on a substrate is divided by a dividing groove referred to as pattern 1 (P1) and a CIS-based light absorption layer
Data Source
AI summary
A CIS-based thin film solar cell has a backside electrode layer that is divided by a pattern (P1), and a CIS-based light absorption layer, and a transparent conductive film are sequentially formed on a substrate. The backside electrode layer comprises an intermediate layer on the surface that is in contact with the CIS-based light absorption layer, the intermediate layer being composed of a compound of a metal that constitutes the backside electrode layer and a group VI element that constitutes the CIS-based light absorption layer; the intermediate layer comprises a first intermediate layer portion which is formed on the upper surface and a second intermediate layer portion which is formed on the lateral surface that and faces the pattern (P1); and the film thickness of the second intermediate layer portion is larger than the film thickness of the first intermediate layer portion.