Chalcopyrite Solar Cell Supply Layer and Diffusion Barrier
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Solution Overview
Problem
The diffusion of Ia group elements like sodium, potassium, and lithium from a compound layer into the circuit layer in photoelectric conversion devices using chalcopyrite-type semiconductors degrades the characteristics of thin film transistors, leading to reliability issues and reduced photoelectric conversion efficiency.
Innovation Solution
A photoelectric conversion device structure is introduced, featuring a circuit layer, a photoelectric conversion layer, a supply layer containing Ia group elements, and a protective layer made of silicon nitride between the supply and circuit layers to prevent diffusion, with the supply layer being silicon oxide, enhancing photoelectric conversion efficiency while maintaining the integrity of the transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a compound layer containing Ia group element is provided between the circuit layer and the photoelectric conversion layer to improve photoelectric conversion efficiency, then the photoelectric conversion efficiency is improved, but the Ia group element diffuses into the circuit layer and degrades the characteristics of the thin film transistor
Solution Approach 1:
A protective layer is introduced as an intermediary between the supply layer containing Ia group element and the circuit layer. This protective layer prevents the harmful diffusion of Ia group elements into the transistor while allowing the supply layer to maintain its function of improving photoelectric conversion efficiency through controlled diffusion into the photoelectric conversion layer.
Solution Approach 2:
The structure is segmented into distinct functional layers: a protective layer specifically positioned between the supply layer and circuit layer. This segmentation isolates the circuit layer from harmful elements while preserving the beneficial functions of the supply layer in the photoelectric conversion process.
2Productivity
If the compound layer is formed of an alkali compound such as Na3AlF6 to improve photoelectric conversion efficiency, then the photoelectric conversion efficiency is improved, but the alkali elements diffuse into the semiconductor layer of the thin film transistor causing degradation and errors in characteristics
Solution Approach 1:
The protective layer serves as a mediator that blocks the diffusion path of alkali elements from the supply layer to the transistor semiconductor layer, preventing characteristic degradation while preserving the photoelectric conversion enhancement benefits.
Solution Approach 2:
The protective layer provides localized protection specifically at the interface between the supply layer and circuit layer, where the harmful diffusion occurs, without interfering with the beneficial processes in other regions of the device.
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 structure effectively improves photoelectric conversion efficiency by allowing Ia group element diffusion into the photoelectric conversion layer while preventing its diffusion into the circuit layer, thereby maintaining transistor reliability and preventing degradation.
Implementation Method 1
a protective layer which is provided between the supply layer and the circuit layer to prevent diffusion of the Ia group element to the circuit layer
Implementation Method 2
when the Ia group element contained in the supply layer diffuses to the photoelectric conversion layer, the photoelectric conversion efficiency is improved
Implementation Method 3
Since a silicon oxide and a silicon nitride have high adhesion to each other, in the above structure, the supply layer can be advantageously prevented from being peeled away from the protective layer
Data Source
AI summary
A circuit layer is formed on a surface of a substrate and includes a transistor. A photoelectric conversion element includes a photoelectric conversion layer of a chalcopyrite-type semiconductor provided between a first electrode and a second electrode. A supply layer is formed between the circuit layer and the photoelectric conversion layer and contains an Ia group element. Diffusion of the Ia group element to the photoelectric conversion layer improves the photoelectric conversion efficiency. A protective layer is formed between the supply layer and the circuit layer and prevents the diffusion of the Ia group element to the circuit layer.