Solvent polarity-induced photoluminescence enhancement (SPIPE): A method enables several-fold increase in quantum yield of silicon nanoparticles
silicon nanoparticles, quantum yield, fluorescent, surface ligand, solvent polarity
Fluorescent silicon nanoparticles (SiNPs) bring exciting opportunities for long-awaited silicon-based optical application, while intrinsic indirect band gap of silicon severely limits photoluminescent quantum yield (PLQY) of SiNPs. To address this critical issue, we herein demonstrate a facile and general method, i.e., solvent polarity-induced photoluminescence enhancement (SPIPE), yielding several-fold increase in quantum yield (QY) of SiNPs. Typically, different kinds of 4-substituented-1,8-naphthalic anhydride molecules, i.e., 4-Br-1,8-naphthalic anhydride (BNA), 4-triphenylamino-1,8-naphthalic anhydride (TPNA), and 4-dimethylamino-1,8-naphthalic anhydride (DMNA), are rationally designed and synthesized, which serve as surface ligands for the production of BNA-, TPNA-, and DMNA-capped small-sized (diameter: ~ 3.8–5.8 nm) SiNPs with QY of ~ 8%, ~ 15%, ~ 16%, respectively. Of particular significance, QY of the resultant SiNPs could be greatly enhanced from ~ 10% to ~ 50% through the SPIPE strategy. Taken together with the theoretical calculation and the results of time-correlated single photon counting, we reveal that actived excited-state charge transfer interactions between surface-covered ligand and silicon oxide coating would be responsible for the observed QY enhancement. Moreover, other five kinds of solvents (i.e., methanol, isopropanol, dimethyl sulfoxide, N,N-dimethylformamide, and acetonitrile) are further employed for the SiNPs treatment, and similar improvement of QY values are observed, convincingly demonstrating the universal evidence of SPIPE of the SiNPs.
Tsinghua University Press
Xiao-Bin Shen,Bin Song,Bei Fang,Xiao Yuan,You-Yong Li,Shun-Yi Wang,Shun-Jun Ji,Yao He, Solvent polarity-induced photoluminescence enhancement (SPIPE): A method enables several-fold increase in quantum yield of silicon nanoparticles. NanoRes.2019, 12(2): 315–322