高度结晶的氮化碳(HCCN)纳米片在光电转换领域中表现出巨大的进步潜力。然而,充分发挥他们的潜力,彻底了解基本的激子光物理过程是至关重要的。这里,使用稳态和时间分辨PL光谱研究了HCCN纳米片和无定形聚合氮化碳(PCN)的温度依赖性激子光致发光(PL)。确定HCCN的激子结合能为109.26meV,低于PCN(207.39meV),这归因于HCCN的有序堆叠结构,电子和空穴之间的库仑相互作用较弱。随着温度的升高,在HCCN和PCN上都观察到PL寿命明显减少,这归因于增强的电子-声子耦合效应对载流子捕获的热激活。确定HCCN的热活化能为102.9meV,接近PCN的值,由于它们相同的波段结构。通过波长相关的PL动力学分析,我们已经确定HCCN的PL发射来自以下跃迁:σ*-LP,π*-π,和π*-LP,由于LP状态的高激发态密度,其中π*-LP跃迁主导了发射。这些结果表明,高结晶度对HCCN材料的激子发射的影响,从而扩大其在光电转换领域的潜在应用。
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Highly-crystallized carbon nitride (HCCN) nanosheets exhibit significant potential for advancements in the field of photoelectric conversion. However, to fully exploit their potential, a thorough understanding of the fundamental excitonic photophysical processes is crucial. Here, the temperature-dependent excitonic photoluminescence (PL) of HCCN nanosheets and amorphous polymeric carbon nitride (PCN) is investigated using steady-state and time-resolved PL spectroscopy. The exciton binding energy of HCCN is determined to be 109.26 meV, lower than that of PCN (207.39 meV), which is attributed to the ordered stacking structure of HCCN with a weaker Coulomb interaction between electrons and holes. As the temperature increases, a noticeable reduction in PL lifetime is observed on both the HCCN and PCN, which is ascribed to the thermal activation of carrier trapping by the enhanced electron-phonon coupling effect. The thermal activation energy of HCCN is determined to be 102.9 meV, close to the value of PCN, due to their same band structures. Through wavelength-dependent PL dynamics analysis, we have identified the PL emission of HCCN as deriving from the transitions:σ*-LP,π*-π, andπ*-LP, where theπ*-LP transition dominants the emission because of the high excited state density of the LP state. These results demonstrate the impact of high-crystallinity on the excitonic emission of HCCN materials, thereby expanding their potential applications in the field of photoelectric conversion.