Surface Defects and Symmetry Breaking Impact on the Photoluminescence of InP Quantum Dots

To fully uncover the potential of indium phosphide (InP)
quantum
dots (QDs) for optoelectronics, it is crucial to understand how surface
defects impact their photoluminescence (PL). To address this question,
we investigate the excitonic properties of defective InP QDs using
two-component density functional theory and screened configuration
interaction singles. In agreement with earlier observations, we identify
3-fold coordinated phosphorus surface atoms, which function as hole
traps, as the major contributors to PL. Additionally, we find that
electron traps of 3-fold coordinated indium atoms, quenching the band-edge
PL, can further contribute to trap PL, if they lie within the single-particle
gap. Importantly, our calculations reveal that surface-induced symmetry
breaking leads to fundamentally different exciton fine structures
in excellent agreement with measurements. This study underscores the
significant influence of surface imperfections on InP QD PL and provides
a refined framework for interpreting their optical properties.