Research / 2020 / Article / Fig 4

Research Article

Near-Infrared-Excitable Organic Ultralong Phosphorescence through Multiphoton Absorption

Figure 4

Proposed mechanism of MPA-OURTP and photophysical properties and aggregation structures of DCzB and DPAB powders. (a) Mechanisms of OURTP and MPA-OURTP. (b) Design principles of MPA-OURTP molecules by integrating intra- and intermolecular CT characters into H-aggregations in a quadrupolar D-A-D skeleton. (c, d) SSPL (blue) and OURTP (pink) spectra of the (c) DCzB and (d) DPAB powders excited by 365 nm UV light and 800 nm NIR laser. Insets show the corresponding molecular structures. (e) The logarithmic plots of the integrated emission intensity versus the 800 nm laser power. (f) OURTP lifetime decay profiles at 475, 495, and 525 nm for DCzB (top) and at 400 and 458 nm for DPAB (bottom) excited by 365 nm UV light. (g) Molecular arrangements in single crystals of DCzB (left) and DPAB (middle) with representative molecular packing structures.