Thiol capped colloidal CdTe quantum dots synthesized using laser ablation

Semiconductor quantum dots [QD] have shown a great number of applications from fluorescent markers to solar cell devices. Colloidal systems have been usually obtained through chemical synthesis, that have to be devoleped for each material. The best quality QDs have been obtained with non-aqueous solution and non-physiological pH, requiring a posterior processing to be used in biology, for example. In contrast, the same physical synthetic method, such as laser ablation, would be applied to any semiconductor, metallic or dielectric material. Colloidal QD can be obtained by laser ablation of a target inside any solvent, given this method a very large flexibility. The fluorescence efficiency, however, depend on the surface traps and stability of colloids. The usual method to avoid surface traps is to grow a cap layer to passivate its surface and, at the same time, stabilize the colloid, sterically or electrostatically. In this work we report a novel technique for obtain thiol capped CdTe colloidal quantum dots in one step. A target immerse in a solution of ethanol and 3-mercaptopropyltrimethoxysilane (MPS), or thiol, was hit by a nanosecond 532 nm laser. With this assembly CdTe luminescent QDs were obtained. The colloid photoluminescence and other optical and structural properties are studied.