Pan Yatao, Wei Zhongran, Ma Mengdi, Zhang Xin, Chi Zhen, He Yulu, Wang Xiaojuan, Ran Xia, Guo Lijun
School of Physics and Electronics, International Joint Research Laboratory of New Energy Materials and Devices of Henan Province, Henan University, Kaifeng 475004, China.
Academy for Advanced Interdisciplinary Studies, State Key Laboratory of Crop Stress Adaptation and Improvement, School of Physics and Electronics, Henan University, Kaifeng 475004, China.
Nanoscale. 2022 Apr 14;14(15):5794-5803. doi: 10.1039/d2nr00211f.
Carbon dots (CDs) have attracted extensive attention for their unique properties and promising applications in many fields. Many efforts have been made to improve the optical and physicochemical properties of CDs using an atomic doping strategy; however, the photoelectric properties of CD-based devices have been less studied and the photocurrent density is far from satisfactory for practical operation. Deep understanding of the doping effects on the electronic structure and photophysical properties of CDs is fundamental and essential for effectively improving the optical and photoelectrical performance of CD-based devices. Here, we have synthesized nitrogen (N) and phosphorus (P) co-doped CDs (N, P-CDs) through a one-step hydrothermal approach, and systematically investigated the effects of P-dopants on the improved optical and photoelectric properties of N, P-CDs. The introduction of P atoms into N-CDs significantly changes the electronic structure and extends the absorption spectral region, enhancing the light-harvesting ability of N, P-CDs. Meanwhile, the regulated carrier dynamics have been investigated using time-resolved fluorescence and transient absorption spectroscopy. We found that the carrier recombination was decreased with introducing P atoms, and the photogenerated electrons in the higher excited states could be efficiently transferred to the lowest excited state. Moreover, the photocurrent density of N, P-CDs was increased by twelve times compared with that of N-CDs. Therefore, the effective doping of P atoms can significantly regulate the electronic structure, optical properties, carrier dynamics and photoelectric conversion of N, P-CDs. The achieved broadband light-harvesting, good photoelectric properties and photostability of the as-prepared N, P-CDs demonstrate an important example of P-doping to improve the optical and photoelectrical properties of CD-based devices.
碳点（CDs）因其独特的性质以及在许多领域的广阔应用前景而备受关注。人们已做出诸多努力，采用原子掺杂策略来改善碳点的光学和物理化学性质；然而，基于碳点的器件的光电性质研究较少，且光电流密度远不能满足实际应用的要求。深入理解掺杂对碳点电子结构和光物理性质的影响，对于有效提高基于碳点的器件的光学和光电性能至关重要。在此，我们通过一步水热法合成了氮（N）和磷（P）共掺杂的碳点（N，P-CDs），并系统研究了P掺杂剂对N，P-CDs光学和光电性能改善的影响。将P原子引入N-CDs中显著改变了电子结构，扩展了吸收光谱区域，增强了N，P-CDs的光捕获能力。同时，利用时间分辨荧光和瞬态吸收光谱研究了调控后的载流子动力学。我们发现，引入P原子后载流子复合减少，处于较高激发态的光生电子能够有效地转移到最低激发态。此外，与N-CDs相比，N，P-CDs的光电流密度提高了12倍。因此，P原子的有效掺杂能够显著调控N，P-CDs的电子结构、光学性质、载流子动力学和光电转换。所制备的N，P-CDs实现了宽带光捕获、良好的光电性质和光稳定性，这是P掺杂改善基于碳点的器件的光学和光电性质的一个重要实例。
