Bright Long-Lived Luminescence of Silicon Nanocrystals Sensitized by Two-Photon Absorbing Antenna

Abstract

Summary Silicon nanocrystals of the average diameter of 5 nm, functionalized with 4,7-di(2-thienyl)-2,1,3-benzothiadiazole chromophores (TBT) and dodecyl chains, exhibit near-infrared emission upon one-photon (1P) excitation at 515 nm and two-photon (2P) excitation at 960 nm. By using TBT chromophores as an antenna we were able to enhance both 1P and 2P absorption cross-sections of the silicon nanocrystals to more efficiently excite their long-lived luminescence. These results chart a path to two-photon-excitable imaging probes with long-lived oxygen-independent luminescence - a rare combination of properties that should allow for a substantial increase in imaging contrast.

Two‐Photon‐Excited Silica and Organosilica Nanoparticles for Spatiotemporal Cancer Treatment

“…The potential of 3D‐resolved two‐photon‐actuated nanomedicine has been exploited via various nanomaterials such as semiconductor and carbon nanodots, polymeric, organic, silicon, gold, graphene and graphene oxide, silica hybrid, and other inorganic nanomaterials. What are the advantages of silica‐based nanoparticles?…”

Improved photon absorption in dye-functionalized silicon nanocrystals synthesized via microwave-assisted hydrosilylation

“…Locritani et al demonstrated that bonded pyrene molecules can increase brightness of SiNc emission by almost 300% at 378 nm excitation. [29][30][31][32][33] In addition, Fermi et al indicated that a porphyrin chromophore can be also used as antenna for SiNc. However, a significant decrease in PLQY from 40% (for bare SiNc) to 8% (for the conjugates with the porphyrin) was observed upon excitation at 427 nm.…”

“…However, a significant decrease in PLQY from 40% (for bare SiNc) to 8% (for the conjugates with the porphyrin) was observed upon excitation at 427 nm. 33 Recently, SiNc with attached diphenyl anthracene were used to improve optical properties of luminescent solar concentrators utilizing SiNc PL. 34 In our previous work, we have demonstrated that microwave-assisted hydrosilylation (MAH) method can produce SiNc exhibiting a PLQY of up to 40% and excellent long-term stability (6 months without decrease of PLQY).…”

Measurement of Two‐Photon Absorption of Silicon Nanocrystals in Colloidal Suspension for Bio‐Imaging Applications

“…Moreover, PL from ncSi in the size range of interest is sufficiently red‐shifted from the absorption bands that it also falls within the bio‐transparency window. Fluorescent ncSi, including those composed of porous silicon and dye‐sensitized ncSi, have been shown to be useful for 2PA bio‐imaging …”