Communication: Non-radiative recombination via conical intersection at a semiconductor defect.

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Electronic excitations in semiconductors can localize at defects, often preceding energy dissipation via non-radiative (NR) decay.
• Many molecular systems are known to undergo NR decay through conical intersections, a process critical for understanding photophysical pathways.

Purpose of the Study:

• To directly simulate the fast and efficient non-radiative decay process occurring at a specific semiconductor defect.
• To investigate the role of a silicon epoxide defect in the photoluminescence (PL) of silicon nanocrystals.

Main Methods:

• Direct simulation of electronic excitation dynamics.
• Computational modeling of conical intersection pathways in semiconductor defects.

Main Results:

• Successfully simulated fast and efficient non-radiative decay via a conical intersection at a silicon epoxide defect.
• The silicon epoxide defect is proposed to selectively quench photoluminescence in silicon nanocrystals with band gaps exceeding approximately 2.8 eV.

Conclusions:

• The silicon epoxide defect acts as a critical site for non-radiative decay in silicon nanocrystals.
• This defect influences both the yield and energy of photoluminescence in oxidized silicon nanocrystals, impacting their optical properties.