Gradient Oxygen Amorphous Silicon Photovoltaic Device
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Solution Overview
Problem
Existing photovoltaic devices with intrinsic amorphous silicon layers between crystalline and amorphous silicon layers face challenges in reducing defect density and carrier recombination, which affects output characteristics.
Innovation Solution
A photovoltaic device structure with a substantially intrinsic second amorphous silicon layer having distinct oxygen concentration profiles, where one section near the crystalline silicon side has a low oxygen concentration to minimize impurities and defects, and another section near the amorphous silicon layer side has a higher oxygen concentration to enhance n-type properties and internal electric field, improving carrier separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen concentration is increased in the intrinsic amorphous silicon layer near the crystalline silicon interface, then defect density is reduced and carrier recombination is suppressed, but oxygen acts as an impurity that degrades material quality
Solution Approach 1:
The patent applies local quality by creating distinct oxygen concentration zones within the intrinsic amorphous silicon layer. The first section (near crystalline silicon) maintains low oxygen concentration (≤10^20 cm^-3) to preserve material quality, while the second section (near amorphous silicon layer) has higher oxygen concentration (≥10^20 cm^-3) to reduce defects. This spatial differentiation of oxygen concentration allows simultaneous optimization of both material purity and defect reduction.
2Reliability
If oxygen concentration is increased in the intrinsic amorphous silicon layer, then n-type properties and internal electric field are enhanced for better carrier separation, but oxygen acts as an impurity that increases carrier capture
Solution Approach 1:
The patent uses local quality to position high oxygen concentration (≥10^20 cm^-3) specifically in the second section near the amorphous silicon layer to enhance n-type properties and internal electric field for improved carrier separation. The first section near crystalline silicon maintains low oxygen concentration (≤10^20 cm^-3) to minimize carrier capture. This localized differentiation resolves the contradiction between needing oxygen for carrier separation and avoiding oxygen-induced carrier capture.
Solution Approach 2:
The intrinsic amorphous silicon layer acts as an intermediary between crystalline silicon and amorphous silicon layer. By controlling oxygen concentration gradients within this intermediate layer, the patent mediates between the requirements of the crystalline side (low oxygen for quality) and the amorphous side (high oxygen for n-type properties and carrier separation), allowing both interfaces to function optimally.
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 reduces carrier capture on the crystalline silicon side and enhances carrier separation on the amorphous silicon side, leading to improved output characteristics, including increased open voltage, short-circuit current, and cell output.
Implementation Method 1
a photovoltaic device including a substantially intrinsic second amorphous silicon layer located between crystalline silicon and a first amorphous silicon layer
Data Source
AI summary
A photovoltaic device capable of improving an output characteristic is provided. The photovoltaic device includes an n-type single-crystal silicon substrate, a p-type amorphous silicon substrate, and a substantially intrinsic i-type amorphous silicon layer disposed between the n-type single-crystal silicon substrate and the p-type amorphous silicon layer. The i-type amorphous silicon layer includes: a first section which is located on the n-type single-crystal silicon substrate side, and which has an oxygen concentration equal to or below 1020 cm−3; and a second section which is located on the p-type amorphous silicon layer side, and which has an oxygen concentration equal to or above 1020 cm−3.