Amorphous Oxide Buffer Layer for Solar Cell Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photoelectric conversion devices, such as solar cells with CIS thin films, face issues with current leakage due to damage and crystal defects, especially when a reverse bias is applied, which is not effectively addressed by existing buffer layers like crystalline CdS films.
Innovation Solution
Incorporating an amorphous oxide semiconductor layer with a larger band gap than the p-type compound semiconductor film, made of Group 12 and 13 elements like In, Ga, and Zn, between the light absorption layer and the window layer, acts as a high-resistance buffer layer, reducing leakage by concentrating the electric field and eliminating crystal defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a crystalline CdS buffer layer is formed by solution growth method, then high coating power and film formation is achieved, but crystal defects occur causing current leakage
Solution Approach 1:
The patent changes the physical state parameter of the buffer layer from crystalline to amorphous. The amorphous oxide semiconductor layer eliminates crystal defects inherent in crystalline structures while maintaining effective buffer layer functionality, thereby preventing current leakage at defect sites.
Solution Approach 2:
The patent uses a composite structure combining the amorphous oxide semiconductor layer with the p-type compound semiconductor light absorption layer. This composite approach allows the buffer layer to provide both mechanical protection and electrical isolation without the drawbacks of crystallineCdS.
2Productivity
If the buffer layer resistance varies when receiving light, then photoelectric response occurs, but electric field concentration is reduced
Solution Approach 1:
The patent changes the optical parameter of the buffer layer by selecting amorphous oxide semiconductor with appropriate band gap. This material has lower light absorption compared to crystalline CdS, maintaining higher resistivity under illumination and enabling better electric field concentration while still allowing sufficient light transmission for photoelectric 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
This configuration stabilizes photoelectric conversion even under reverse bias, reduces dark current, and enhances light absorption efficiency by increasing the band gap, leading to a more reliable and sensitive photoelectric conversion device suitable for electronic apparatus like image sensors.
Implementation Method 1
the electric field can be concentrated in the oxide semiconductor layer when a forward bias is applied
Implementation Method 2
a photoelectric conversion device that converts light energy into electrical energy
Data Source
AI summary
A photoelectric conversion device includes circuit portions disposed on a substrate, a first electrode electrically connected to one of the circuit portions, an optically transparent second electrode opposing the first electrode, and a photoelectric conversion portion disposed between the first electrode and the second electrode. The photoelectric conversion portion has a multilayer structure including a light absorption layer made of a p-type compound semiconductor film having a chalcopyrite structure, an amorphous oxide semiconductor layer, and a window layer made of an n-type semiconductor film.