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.