Scalable CIGS Solar Cells Employing a New Device Design of Nontoxic Buffer Layer and Microgrid Electrode

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Transparent conductive oxides (TCOs) limit the efficiency of large-area copper indium gallium selenide (CIGS) solar cells due to poor electrical properties.
• Developing novel top electrodes with high transmittance and conductivity is crucial for high-efficiency, large-area CIGS devices.

Purpose of the Study:

• To design a microgrid/TCO hybrid electrode to minimize optical and resistive losses in CIGS solar cells.
• To improve device efficiency by replacing the conventional CdS buffer with a dry-processed ZnMgO (ZMO) buffer, reducing short-wavelength parasitic absorption.

Main Methods:

• Fabrication of a microgrid/TCO hybrid electrode for CIGS solar cells.
• Implementation of a dry-processed wide-band gap ZnMgO (ZMO) buffer layer.
• Optimization of the ZMO buffer and microgrid/TCO electrode combination.

Main Results:

• A small device area (5 mm × 5 mm) achieved a maximum efficiency of 20.5% with antireflection layers.
• Large-area CIGS solar cells (20 mm × 70 mm) reached an efficiency of 19.7% with the microgrid/TCO hybrid electrode and antireflection layers.

Conclusions:

• The study demonstrates the potential of microgrid electrodes for achieving high-efficiency, large-area CIGS solar cells.
• The combination of a microgrid/TCO hybrid electrode and ZMO buffer significantly enhances CIGS solar cell performance and scalability.