Hybrid CZTSSe Photovoltaic Device for Efficiency
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Solution Overview
Problem
Cu-Zn-Sn-Se (CZTSSe) thin film solar cells face limitations such as low open circuit voltage, high bulk defect states, tail states, Fermi level pinning, and low fill factor due to interface recombination and series resistance, limiting their power conversion efficiency.
Innovation Solution
A hybrid photovoltaic device is developed with a Cu-Zn-Sn-Se (CZTSSe) absorber layer combined with a high-performance semiconductor layer like CIGSSe, featuring different buffer and absorber layer configurations (Type I, II, and III) to enhance power conversion efficiency, utilizing a buffer layer and transparent conductive contact layer to optimize performance and reduce material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CZTSSe absorber layer is used to replace rare elements like indium, then material cost and availability are improved, but power conversion efficiency deteriorates
Solution Approach 1:
The patent employs a hybrid absorber structure combining CZTSSe layer with a second semiconductor material layer (such as CIGSSe or CdTe) to create a composite absorber. This composite structure leverages the earth-abundant advantage of CZTSSe while incorporating the high efficiency characteristics of the second material, thereby resolving the contradiction between material availability and power conversion efficiency.
2Ease of manufacture
If buffer-absorber interface is formed in CZTSSe solar cells, then device structure is completed, but interface recombination increases causing low open circuit voltage
Solution Approach 1:
The patent introduces an intermediate layer or modifies the buffer layer composition to act as a mediator between the buffer and absorber layers. This intermediary structure reduces interface recombination by improving band alignment and reducing defect states at the interface, thereby maintaining device structure completion while improving open circuit voltage.
Solution Approach 2:
The patent modifies the composition, thickness, or crystalline structure parameters of the buffer layer or interface region to optimize the buffer-absorber interface. By changing these parameters, the interface quality is improved, reducing recombination losses while maintaining the necessary device structure.
3Productivity
If series resistance is reduced to improve fill factor, then device complexity increases due to additional layers or modifications
Solution Approach 1:
The patent optimizes parameters such as layer thickness, doping concentration, or material composition of existing layers to reduce series resistance without adding structural complexity. For example, adjusting the thickness of the buffer layer or modifying the doping profile in the absorber layer can reduce series resistance while maintaining the same device architecture.
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
The hybrid devices achieve higher power conversion efficiency compared to baseline CZTSSe devices, with improved open circuit voltage, current density, and fill factor, enabling performance-material cost optimization for large-scale deployment of thin film chalcogenide solar cells.
Implementation Method 1
Hybrid CZTSSe photovoltaic device
Data Source
AI summary
A photovoltaic device includes a first contact and a hybrid absorber layer. The hybrid absorber layer includes a chalcogenide layer and a semiconductor layer in contact with the chalcogenide layer. A buffer layer is formed on the absorber layer, and a transparent conductive contact layer is formed on the buffer layer.