The PL property of solution and NPs of DIPT-IC and DIPT-ICF were investigated. As shown in Fig. , the main emission maxima of DIPT-IC and DIPT-ICF have been recorded as 988 nm and 1014 nm, respectively, while the emission of their NPs redshifted to 1090 nm and 1078 nm, respectively, due to the enhanced intermolecular interactions in aggregate state. It is worthy to note that both DIPT-IC and DIPT-ICF as well as their NPs exhibited shoulder peaks extended to the NIR-IIa region (1300-1400 nm), which were much favorable to achieve a deep penetration depth for in vivo imaging. PLQY (ΦPL) of DIPT-IC and DIPT-ICF were determined to be 1.86% and 0.66%, respectively, both of which are higher than the reference molecule IR-26 (ΦPL = 0.5%) (Fig. ). Although the PLQY of DIPT-ICF is slightly lower than that of DIPT-IC, its brightness is much higher than that of DIPT-IC since brightness is the production of molar absorptivity and PLQY , while the molar absorptivity of DIPT-ICF is 3.4 times higher than that of DIPT-IC. The aggregation-enhanced emission properties (Fig. ) and high brightness of DIPT-ICF demonstrates its potential as high brightness fluorescence nano contrast agent.