Biomimetic Conical Microhole Architecture Enabling 18.4%-Efficient Silicon Solar Cells with Superior Durability

Area of Science:

• Materials Science
• Photovoltaics
• Nanotechnology

Background:

• Three-dimensional structured silicon solar cells offer enhanced light absorption but suffer from mechanical fragility.
• Microwire architectures provide optical benefits but face structural failure due to high aspect ratios and mechanical stress.

Purpose of the Study:

• To develop mechanically robust, high-efficiency silicon solar cells by inverting the microwire concept.
• To optimize conically etched microhole arrays (CEMA) for improved light absorption and carrier collection.

Main Methods:

• Rigorous coupled-wave analysis simulations to optimize CEMA geometric parameters.
• A specialized fabrication process combining deep reactive ion etching and wet chemical etching.
• Mechanical stress testing and optical/electrical performance characterization.

Main Results:

• Optimized CEMA structures demonstrated reduced surface reflection (<5% weighted average reflectance) and preserved carrier collection.
• The honeycomb-like CEMA architecture exhibited exceptional mechanical stability.
• Achieved high performance metrics: 40-48 mA/cm² short-circuit current density, 599 mV open-circuit voltage, and 18.4% power conversion efficiency.

Conclusions:

• Conically etched microhole arrays (CEMA) provide a mechanically robust alternative to microwire solar cells.
• The CEMA design maintains optical and electrical advantages while significantly improving structural integrity.
• This work presents a practical pathway toward durable, high-efficiency silicon photovoltaics.