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

Herein, we report a method to produce luminescent silicon nanocrystals (SiNc) that strongly absorb ultra-violet–visible light (300–550 nm) and emit in the near-infrared range (700–1000 nm) with a high photo-luminescence quantum yield (PLQY). Using microwave-assisted hydrosilylation and employing reactivechromophores–such as ethenyl perylene, ethynyl perylene and ethylene-m-phenyl BODIPY–we areable to achieve a 10- and 3-fold enhancement of the absorption in the blue and green spectral range,respectively. The investigated dyes function both as passivating agents and highly efficient antenna, whichabsorb visible light and transfer the energy to SiNc with an efficiency of >95%. This enhanced absorptionleads to a significant photoluminescence enhancement, up to∼270% and∼140% under excitation withblue and green light, respectively. Despite the gain in absolute brightness of the emission, we demon-strate that back energy transfer from the SiNc to the dyes leads to a decrease in the PLQY for dye-modified SiNc, as compared to unmodified SiNc. The synthesis of the SiNc-dye conjugates opens up newpossibilities for applications of this abundant and non-toxic material in thefield of solar energy harvesting,optical sensing and bioimagingviaachieving strong NIR PL excited with visible light.