The short wave near-infrared fluorescence properties of two p-azaquinodimethane (p-AQM)-based conjugated polymers

Abstract

The absorption, scattering, and autofluorescence of biological tissues in short-wave infrared region (SWIR, 900–1700[Formula: see text]nm) are relatively low, so SWIR fluorescence usually has deeper penetration into living tissues, and can show a higher signal-to-noise ratio when used for imaging in vivo. However, there are few types of organic SWIR fluorescent materials currently. In this work, [Formula: see text]-azaquinodimethane ([Formula: see text]-AQM) with a quinoid structure is used as the acceptor unit, and carbazole or fluorene with sp3 hybridization are used as the donor units, two conjugated polymers were synthesized. The quinone structure is conducive to the redshift of absorption and fluorescence spectra, and the sp3 hybridization structure is conducive to weakening the aggregation quenching of polymer fluorescence. PF and PCz exhibited absorption peaks of 492[Formula: see text]nm and 508[Formula: see text]nm, respectively. The emission peaks of the two polymers are 920[Formula: see text]nm and 950[Formula: see text]nm, respectively, both in the short-wave near infrared region. The quantum yield (QY) of PF and PCz is 0.4% and 0.3%, respectively.

Recent advances in small molecular design for high performance non-fullerene organic solar cells

“…Conjugated polymers have been developed for many years and have been widely used in photovoltaics 14,51 and other fields. [52][53][54][55] Compared with conjugated polymers, small molecule materials have the advantages of high purity, definite chemical structure, and good repeatability. Smallmolecule donor materials have been developed for many years, 56,57 but the development of small-molecule acceptor materials was relatively slow until the emergence of nonfullerene fused-ring electron acceptors (FREAs), which promoted the improvement of photoelectric conversion efficiency of polymer donor/small molecule acceptor OSCs.…”

Dithieno[3,2-b:2′,3′-d]silole-based conjugated polymers for bioimaging in the short-wave infrared region

“…Prof. Hongjie Dai rst reported the application of a D-A type conjugated polymer named as pDA as a SWIR uorescent material in the eld of SWIR uorescence imaging in 2014. 8 Since then, a large number of D-A type conjugated polymers have been used in biomedical elds such as SWIR uorescence imaging, 10,27,28 photothermal therapy, [29][30][31] photoacoustic imaging [32][33][34] and photodynamic therapy. 35,36 However, the uorescence quantum efficiency of D-A type conjugated polymer uorescent materials still needs to be improved.…”

“…41 The effect of this strategy on the improvement of uorescence quantum efficiency is not obvious. The second strategy is introducing donor units with sp 3 hybrid conguration 27,37 such as 4H-cyclopenta[2,1-b:3,4-b 0 ]dithiophene (CPDT). 37 The sp 3 hybrid has a tetrahedral conguration.…”

“…The highest SWIR fluorescence quantum efficiency of AIE material has been higher than 10%. 40 In recent years, we have tried to solve this problem through non-AIE methods, 27,28,37,41 rational molecular structure design has been used to alleviate the aggregation of polymers, thereby reducing the ACQ, and then the fluorescence quantum efficiency can be improved. Two strategies had been used to weaken polymer accumulation in our previous work.…”

Introduction to the Special Issue on Two-Dimensional Materials and Their Biophotonic Applications

“…2 Zhimei Wei et al comprehensively introduced biological nanober materials prepared by electrospinning for potential antibacterial applications. 3 In addition, four original studies presented in this issue range from excellent near-infrared°uorescence probes [4][5][6] to rapid label-free SERS detection. 7 Overall, they represent a series of works with di®erent focuses not only on the emerging 2D materials nanotechnology, but also on their potential applications in biophotonics and related research¯elds.…”