CIGS Solar Absorber Sublayers for Roll-to-Roll Defect Control
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Solution Overview
Problem
Traditional methods for fabricating CIGS photovoltaic devices are slow, prone to defects, and costly due to high deposition rates that propagate defects through the entire thickness of the absorber layer, leading to reduced efficiency and increased manufacturing costs, especially in roll-to-roll processing for large-area modules.
Innovation Solution
The approach involves depositing multiple sublayers of IB-IIIB-VIB semiconductor materials in vacuo using physical vapor deposition sources, with each sublayer being of lesser thickness than the total desired thickness, allowing for higher substrate transport speeds and reducing defect propagation, and enabling adjustable chemistry for enhanced electrical and physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional in vacuo deposition methods are used to create CIGS absorber layers, then high performance can be achieved, but fabrication speed is slow and costs are high
Solution Approach 1:
The absorber layer is divided into multiple sequential sublayers, each deposited in a separate deposition zone. This segmentation allows each sublayer to be deposited more quickly while maintaining overall film quality, as defects in one sublayer do not necessarily propagate through the entire thickness.
Solution Approach 2:
The invention transitions from a single deposition zone to multiple deposition zones arranged sequentially along the substrate path. This spatial dimensionality change enables continuous deposition at higher speeds while maintaining film quality through the multi-zone architecture.
2Productivity
If high deposition rates are used to increase productivity, then fabrication speed improves, but defects propagate through the entire absorber layer thickness
Solution Approach 1:
By segmenting the absorber layer into multiple sublayers deposited in separate zones, the invention limits defect propagation to individual sublayers rather than allowing it to affect the entire layer. This enables higher deposition rates in each zone without compromising overall film quality.
Solution Approach 2:
Each deposition zone can be optimized for specific local requirements, allowing high deposition rates in later zones while maintaining quality control. The local quality of each sublayer can be independently managed to prevent defect propagation through the entire structure.
3Productivity
If roll-to-roll processing is implemented for large-area modules, then manufacturing efficiency increases, but maintaining high substrate transport speed while achieving desired film thickness becomes challenging
Solution Approach 1:
The invention uses multiple deposition zones arranged sequentially in the substrate transport direction, enabling high transport speeds by distributing the total deposition thickness across multiple zones rather than requiring one extremely long deposition zone.
Solution Approach 2:
The total absorber layer thickness is segmented into multiple sublayers, each deposited in a separate zone. This allows the substrate to move quickly through each zone while still achieving the required total thickness, maintaining both speed and thickness uniformity.
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 method improves deposition efficiency, reduces short-circuit defects, and allows for adjustable properties in the absorber layer, enhancing the conversion efficiency of photovoltaic devices and accommodating various existing processes, including roll-to-roll processing.
Implementation Method 1
depositing multiple sublayers of IB-IIIB-VIB semiconductor materials in vacuo using physical vapor deposition sources
Data Source
AI summary
A method of manufacture of I-III-VI-absorber photovoltaic cells involves sequential deposition of films comprising one or more of silver and copper, with one or more of aluminum indium and gallium, and one or more of sulfur, selenium, and tellurium, as compounds in multiple thin sublayers to form a composite absorber layer. In an embodiment, the method is adapted to roll-to-roll processing of photovoltaic cells. In an embodiment, the method is adapted to preparation of a CIGS absorber layer having graded composition through the layer of substitutions such as tellurium near the base contact and silver near the heterojunction partner layer, or through gradations in indium and gallium content. In a particular embodiment, the graded composition is enriched in gallium at a base of the layer, and silver at the top of the layer. In an embodiment, each sublayer is deposited by co-evaporation of copper, indium, gallium, and selenium, which react in-situ to form CIGS.