Decoupled front/back dielectric textures for flat ultra-thin c-Si solar cells

Area of Science:

• Materials Science
• Optoelectronics
• Renewable Energy

Background:

• Ultra-thin crystalline silicon (c-Si) solar cells require advanced light management for efficiency.
• Dielectric textures offer a tunable approach to enhance light absorption in silicon.

Purpose of the Study:

• To analyze the optical performance of ultra-thin c-Si slabs with decoupled front titanium-dioxide (TiO2) / back silicon-dioxide (SiO2) dielectric textures.
• To compare the effectiveness of different back reflectors (silver and dielectric modulated distributed Bragg reflector - MDBR) and texturing strategies.

Main Methods:

• Optical analysis of c-Si slabs with front dielectric textures and two types of back reflectors.
• Comparison with state-of-the-art flat c-Si with Mie resonators and textured c-Si with dielectric coatings.
• Evaluation of photo-generated current density under varying optical configurations.

Main Results:

• An optimized front dielectric textured design on a 2-µm flat c-Si slab with MDBR increased photo-generated current density by +6.4% compared to Mie resonators.
• Improved light in-coupling (400-700 nm) and scattering (700-1050 nm) contributed to the enhanced performance.
• Textured dielectric layers reduced photo-generated current density by up to -20.6% compared to textured c-Si, depending on the back reflector.

Conclusions:

• Decoupled front dielectric textures, particularly with MDBR, show significant potential for enhancing light absorption in ultra-thin c-Si solar cells.
• The choice of texturing strategy (dielectric vs. c-Si) and back reflector critically impacts overall device performance.
• Further optimization of dielectric texturing could lead to more efficient and cost-effective silicon solar technologies.