Semiconducting monolayer materials as a tunable platform for excitonic solar cells

Area of Science:

• Materials Science
• Condensed Matter Physics
• Renewable Energy

Background:

• Two-dimensional (2D) monolayer materials offer tunable optical properties and high carrier mobility.
• These properties present opportunities for developing efficient, ultrathin excitonic solar cells.
• Current solar cells often rely on conjugated polymers or small molecule donors.

Purpose of the Study:

• To investigate the potential of hexagonal boron nitride and graphene (CBN) monolayers in excitonic solar cells.
• To explore the tunability of absorber gap, donor-acceptor interface band alignment, and power conversion efficiency.
• To propose novel device architectures utilizing these 2D materials.

Main Methods:

• First-principles density functional theory (DFT) calculations.
• Many-body calculations.
• Simulations of CBN-PCBM fullerene and carbon nanotube acceptor systems.

Main Results:

• CBN monolayers combined with acceptors like PCBM fullerene or carbon nanotubes enable tunable solar cell properties.
• Predicted power conversion efficiency limits for CBN-PCBM devices range from 10-20%, dependent on CBN structure.
• Demonstrated tunability of absorber gap and donor-acceptor interface band alignment.

Conclusions:

• Monolayer materials provide a viable route for creating tunable, efficient, and ultrathin solar cells.
• These materials open up unexplored exciton and carrier transport regimes for solar energy conversion.
• The findings support the development of next-generation solar cell technologies based on 2D materials.