PV cells are made of ___.

• A. Graphene
• B. Silicon
• C. Gallium nitride
• D. Copper

Answer: (B)

Photovoltaic cells rely on a semiconductor with the right bandgap to convert light into electricity. Silicon fits that role well: its bandgap of about 1.1 eV is near ideal for absorbing a broad range of the solar spectrum, which helps generate electron-hole pairs efficiently. Silicon also forms stable, well-understood p-n junctions when doped, enabling effective separation and collection of charges to produce current. It’s abundant and inexpensive, and decades of manufacturing development have optimized crystal quality, surfaces, and interfaces, giving reliable performance and lower costs.

Graphene is an excellent conductor and can serve as a contact layer, but it lacks the suitable bandgap to act as the primary light-absorbing material in a conventional PV cell. Gallium nitride has a wide bandgap, making it great for LEDs and high-power electronics, but it doesn’t absorb visible light as effectively for broad solar energy. Copper is a metal with no bandgap, so it cannot form the necessary semiconductor behavior to generate a photovoltaic current.