Surface polarity controls the optical properties of one-pot synthesized silicon quantum dots

Abstract

The absorption and emission properties of Silicon quantum dots (Si QDs) depend largely on their surface chemistry. While the size of Si QDs is hardly controlled, delicate surface modification is relied to vary the optical properties of Si QDs. Herein, we report a one-pot synthesis of blue-emitting Si QDs followed by chromatography separation into two fractions with distinct absorption and emission properties. The polar fraction showed featureless UV–vis absorption profile and a broad photoluminescence (PL) spectrum with an enhancement in green-yellow region when compared with that of non-polar fraction, which exhibited UV-blue emission. FT-IR and XPS analyses inferred a mechanism that oxidized surfaces (SiOx) added new electronics states via which PL were red-shifted into visible region. The simple separation of easily synthesized Si QDs into colorful Si QDs is of important to deploy non-toxic Si QDs into practical applications.