Multilayer TCO Conductive Layer for Oxidation-Safe Silicon Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The conductivity between the amorphous silicon layer and the transparent conductive film in heterojunction solar cells is deteriorated due to oxidation caused by oxygen and free interstitial oxygen in the transparent conductive film, affecting the efficiency of the cell.
Innovation Solution
A conductive layer comprising multiple TCO layers prepared under specific gas atmospheres with controlled partial pressures of hydrogen and oxygen, including a reductive first atmosphere, a gradient change in gas partial pressures for the second and fourth layers, and a high oxygen atmosphere for the third layer, to enhance conductivity and transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive film is deposited under argon and oxygen atmosphere to adjust resistance and transmittance, then the transmittance and resistance of the film are improved, but the conductivity between the amorphous silicon layer and the transparent conductive film deteriorates
Solution Approach 1:
The transparent conductive film is divided into multiple layers (first TCO layer, second TCO layer, third TCO layer, and fourth TCO layer) with different thicknesses and deposition conditions. The first layer (2-6 nm) is deposited under reducing atmosphere to protect the amorphous silicon layer, while subsequent layers are deposited under oxygen-containing atmospheres to achieve high transmittance and conductivity, thus resolving the contradiction between protecting the silicon layer and achieving good film performance.
Solution Approach 2:
Different regions of the transparent conductive film structure have different oxygen contents and deposition conditions optimized for their specific functions. The first layer has low oxygen content to prevent oxidation of the amorphous silicon layer, while the third layer has high oxygen content to achieve high transmittance. This local optimization of oxygen content in different layers resolves the contradiction between protecting the silicon layer and achieving good optical and electrical properties.
2Illumination intensity
If oxygen is introduced into the transparent conductive film to improve transmittance, then the transmittance is improved, but oxidation of the amorphous silicon layer occurs reducing conductivity
Solution Approach 1:
The first TCO layer is deposited under a reducing atmosphere (argon and hydrogen) before depositing subsequent layers that contain oxygen. This preliminary reducing environment protects the amorphous silicon layer from oxidation before the oxygen-containing layers are deposited, thus preventing oxidation damage while still allowing subsequent layers to provide high transmittance.
Solution Approach 2:
The first TCO layer acts as an intermediary barrier between the amorphous silicon layer and the oxygen-containing environment. By depositing this protective layer first under reducing conditions, it serves as a buffer that prevents oxygen from reaching and oxidizing the amorphous silicon layer, while still allowing the subsequent oxygen-rich layers to be deposited for optimal transmittance.
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 conductive layer achieves improved conductivity with the amorphous silicon layer, high transmittance, and good conductive performance, enhancing the efficiency of heterojunction solar cells.
Implementation Method 1
The first TCO layer, the second TCO layer, the third TCO layer, and the fourth TCO layer are prepared by a physical vapor deposition process
Data Source
AI summary
A conductive layer, comprising a first TCO layer, a second TCO layer, a third TCO layer and a fourth TCO layer which are stacked. The first TCO layer is prepared in a first atmosphere, and the first atmosphere is a mixed gas of argon and hydrogen; the second TCO layer is prepared in a second atmosphere, the second atmosphere is a mixed gas of argon, hydrogen, and oxygen, a partial pressure gradient of hydrogen is reduced, and a partial pressure gradient of oxygen is increased; the third TCO layer is prepared in a third atmosphere, and the third atmosphere is a mixed gas of argon and oxygen; the fourth TCO layer is prepared in a fourth atmosphere, the fourth atmosphere is a mixed gas of argon and oxygen, and a partial pressure gradient of oxygen is decreased.