State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Eastern South Lake Road, Changchun 130033, China.
Nanoscale Horiz. 2019 Jan 1;4(1):175-181. doi: 10.1039/c8nh00258d. Epub 2018 Oct 2.
There has been a long standing debate on the luminescence origination from carbon nanodots (CDs). Herein, we report the solvent dependent piezochromism of CDs by diamond anvil cells experiment. Red- and blue-shift piezochromism were observed in CDs with N,N-dimethylformamide and water as pressure transmitting medium (PTM) with increasing pressure from atmospheric pressure to 25 GPa, which were related to increased π-π stacking and protic-solvent-induced surface chemical structural changes, respectively. Based on theoretical modeling and structural analysis of hydrothermally treated CDs (h-CDs), the reversible and irreversible piezochromism from green emission to blue emission with water as PTM was attributed to pressure induced enhanced intermolecular hydrogen bonding and addition reaction between water molecules and surface electron withdrawing groups on the CDs, respectively. The decreased electron withdrawing ability of the surface chemical structures of CDs further affects their intrinsic luminescence. This work provides a new understanding of the piezochromic luminescence origination from CDs, which is related to the surface related intrinsic luminescence.
关于碳纳米点（CDs）的发光起源，一直存在着长期的争论。在此，我们通过金刚石压腔实验报告了 CDs 溶剂依赖性的压致变色。在 N,N-二甲基甲酰胺和水作为压力传递介质（PTM）的情况下，随着压力从大气压增加到 25 GPa，观察到了 CDs 的红移和蓝移压致变色，这分别与π-π堆积的增加和质子溶剂诱导的表面化学结构变化有关。基于水热处理 CDs（h-CDs）的理论建模和结构分析，在水作为 PTM 的情况下，从绿色发射到蓝色发射的可逆和不可逆压致变色归因于压力诱导的增强的分子间氢键和水分子与 CDs 表面吸电子基团之间的加成反应。CDs 表面化学结构的电子受主能力的降低进一步影响了它们的本征发光。这项工作为理解与表面相关的本征发光有关的 CDs 的压致变色发光起源提供了新的认识。
