Multi-layer transparent conductive layer for solar cell light absorption
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Solution Overview
Problem
Current solar cells face inefficiencies in converting sunlight to electrical energy due to light loss, particularly when incident sunlight is reflected from the rear electrode and re-reaches the transparent conductive layer, necessitating a solution to enhance transmittance and absorption.
Innovation Solution
A multi-layer transparent conductive layer structure with varying oxygen contents and refractive indexes is implemented, comprising a high-oxygen content transmitting layer and a lower-oxygen content conductive layer, with an intermediate layer to maintain crystallinity, allowing for increased light absorption and reduced light loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-layer transparent conductive layer is used, then the structure is simple, but light absorption is insufficient and efficiency is low
Solution Approach 1:
The transparent conductive layer is divided into multiple sub-layers (first transparent conductive sub-layer, second transparent conductive sub-layer, third transparent conductive sub-layer) with different oxygen contents and light absorbing coefficients. This segmentation allows each sub-layer to perform specialized functions: the first sub-layer with high oxygen content provides excellent crystallinity and large crystal grain size, the second sub-layer with intermediate oxygen content balances transmittance and conductivity, and the third sub-layer with low oxygen content provides high light absorption. The combined structure achieves superior overall performance that a single layer cannot provide.
2Reliability
If oxygen content is increased to improve crystallinity, then crystal grain size increases, but light absorbing coefficient decreases
Solution Approach 1:
Different regions of the transparent conductive layer are assigned different oxygen contents to optimize local properties. The first sub-layer near the substrate has high oxygen content (60-80 sccm) to ensure excellent crystallinity and large crystal grain size as a foundation. The second sub-layer has intermediate oxygen content (30-50 sccm) to balance transmittance and conductivity. The third sub-layer at the surface has low oxygen content (10-20 sccm) to maximize light absorption coefficient. This local quality differentiation resolves the contradiction by allowing high crystallinity in the lower layers while maintaining high light absorption in the upper layers.
3Productivity
If a multi-layer structure with different oxygen contents is used, then light absorption and transmittance are improved, but manufacturing complexity increases
Solution Approach 1:
The invention controls the oxygen content parameter during the deposition process to create layers with different properties. By adjusting the oxygen flow rate during deposition (60-80 sccm for the first sub-layer, 30-50 sccm for the second, 10-20 sccm for the third), each sub-layer achieves the desired oxygen concentration without requiring post-deposition treatment. This parameter-based control simplifies manufacturing compared to methods requiring separate deposition processes or thermal treatments, as the oxygen content gradient is achieved in a single continuous deposition process.
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 enhances solar cell efficiency by increasing sunlight transmittance and absorption, maintaining excellent crystallinity and large crystal grain size, and reducing specific resistance, thereby improving overall energy conversion efficiency.
Implementation Method 1
a solar cell that increases efficiency by increasing transmittance of sunlight by forming a transparent conductive layer of the solar cell in a multi-layer structure including a plurality of layers having different oxygen contents and different light absorbing coefficients
Implementation Method 2
The solar cell, which is a device converting light energy into electrical energy using a photovoltaic effect
Implementation Method 3
a solar cell that can increase efficiency by forming a transparent conductive layer of the solar cell in a multi-layer structure including a plurality of layers having different refractive indexes so that incident sunlight is absorbed again into a photoelectric conversion layer
Data Source
AI summary
A solar cell is provided that increases a rate of sunlight absorbed into a photoelectric conversion layer by forming a transparent conductive layer into a plurality of layers having different oxygen contents and different light absorption coefficients, and a manufacturing method thereof. The solar cell includes a substrate, a transparent conductive layer, and a photoelectric conversion layer. The transparent conductive layer includes a first layer having a first light absorption coefficient, and a second layer formed on the first layer and having a second light absorption coefficient higher than the first light absorption coefficient.