Mono- or few-layer black phosphorus (BP) has emerged as a promising photovoltaic and optoelectronic material with realistic applications subjected to instability and short charge carrier lifetime. Experiments show that covalent functionalization can improve the stability, but the underlying mechanism for the prolonged lifetime remains elusive. By performing spin-polarized time domain density functional theory combined with nonadiabatic (NA) molecular dynamics simulations, we demonstrate that BP passivated with both phenyl and nitrophenyl can suppress the nonradiative electron-hole recombination by a factor of 2 and 3, respectively, relative to the pristine system. The slow recombination is due to the interplay between energy gap, NA coupling, and decoherence time, which happens either through a hole-trap-assisted process or in a direct way between a free electron and hole in the spin-up channel. The observations hold in the spin-down channel. The study suggests that the passivating strategy should work for BP and other two-dimensional materials.

中文翻译：

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共价官能化的黑磷极大地抑制了非辐射电荷复合：时域从头算研究。

单层或很少层的黑磷（BP）已经成为一种有前途的光伏和光电材料，其实际应用受到不稳定和载流子寿命短的困扰。实验表明，共价官能化可以提高稳定性，但延长寿命的潜在机制仍然难以捉摸。通过执行自旋极化的时域密度泛函理论与非绝热（NA）分子动力学模拟相结合，我们证明了同时被苯基和硝基苯基钝化的BP可以分别将非辐射电子-空穴复合抑制2到3倍。原始系统。重组缓慢是由于能隙，NA耦合和去相干时间之间的相互作用，这要么通过空穴陷阱辅助过程发生，要么通过自由电子与自旋通道中的空穴之间直接发生。观测值保持在向下旋转的通道中。研究表明钝化策略应适用于BP和其他二维材料。