Optical design of GaN/In(x)Ga(1-x)N/cSi tandem solar cells with triangular diffraction grating

Area of Science:

• Materials Science
• Optoelectronics
• Renewable Energy

Background:

• Group-III-nitride and multiple quantum well-based solar cells are crucial for renewable energy.
• Enhancing optical absorption is key to improving solar cell efficiency.
• Tandem solar cells offer higher efficiency potential by utilizing a broader spectrum of light.

Purpose of the Study:

• To optimize the optical design of GaN/InGaN/cSi dual-junction tandem solar cells for enhanced light absorption.
• To investigate the impact of antireflection coatings, thin-film layers, and diffraction gratings on optical absorption.
• To achieve high light harvesting efficiency in a thin-film solar cell design.

Main Methods:

• Simulations using combined two-dimensional rigorous coupled wave analysis (2D-RCWA) and transfer matrix methods.
• Integrated analysis from semiconductor physics and electromagnetic theory perspectives.
• Optimization of triangular diffraction grating and antireflection coatings.

Main Results:

• A 58% improvement in optical absorption compared to the prototype solar cell.
• Harvesting over 80% of incident light with photon energy greater than the silicon bandgap (hυ > EgSi).
• Demonstrated a functional thin-film design with a total thickness of less than 4 μm.

Conclusions:

• The proposed optical design significantly enhances light absorption in GaN/InGaN/cSi dual-junction tandem solar cells.
• This approach offers a promising pathway for developing highly efficient thin-film solar cells.
• The study provides a novel integrated perspective on optimizing solar cell performance.