Continuous synthesis of high quality CdSe quantum dots in supercritical fluids

Abstract

We demonstrate in here a powerful scalable technology to synthesize continuously high quality CdSe quantum dots (QDs) in supercritical hexane. Using a low cost, highly thermally stable Cd-precursor, cadmium deoxycholate, the continuous synthesis is performed in 400 μm ID stainless steel capillaries resulting in CdSe QDs having sharp full-width-at-half-maxima (23 nm) and high photoluminescence quantum yields (45–55%). Transmission electron microscopy images show narrow particles sizes distribution (σ ≤ 5%) with well-defined crystal lattices. Using two different synthesis temperatures (250 °C and 310 °C), it was possible to obtain zinc blende and würtzite crystal structures of CdSe QDs, respectively. This synthetic approach allows achieving substantial production rates up to 200 mg of QDs per hour depending on the targeted size, and could be easily scaled to gram per hour.