Joung et al. Nanoscale Research Letters 2012, 7:93 http://www.nanoscalereslett.com/content/7/1/93 N A N O E X P R E S S Open Access Facile synthesis of uniform large-sized InP nanocrystal quantum dots using tris(tert- butyldimethylsilyl)phosphine SoMyoung Joung1,2†, Sungwoo Yoon2†, Chang-Soo Han3†, Youngjo Kim2* and Sohee Jeong1* Abstract Colloidal III-V semiconductor nanocrystal quantum dots [NQDs] have attracted interest because they have reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals are limited by difficulties in their synthesis. In particular, it is difficult to control nucleation because the molecular bonds in III-V semiconductors are highly covalent. A synthetic approach of InP NQDs was presented using newly synthesized organometallic phosphorus [P] precursors with different functional moieties while preserving the P-Si bond. Introducing bulky side chains in our study improved the stability while facilitating InP formation with strong confinement at a readily low temperature regime (210°C to 300°C). Further shell coating with ZnS resulted in highly luminescent core-shell materials. The design and synthesis of P precursors for high-quality InP NQDs were conducted for the first time, and we were able to control the nucleation by varying the reactivity of P precursors, therefore achieving uniform large-sized InP NQDs. This opens the way for the large-scale production of high-quality Cd-free nanocrystal quantum dots. Keywords: phosphorus precursor, indium phosphide nanocrystal quantum dot, colloidal synthesis, nontoxic Introduction Colloidal III-V semiconductor nanocrystals have attracted interest within the decade due to their less ionic lattice and reduced toxicity compared to II-VI com- pounds [1-4]. However, the study and application of III- V semiconductor nanocrystals are limited by the diffi- culty in their synthesis. It is very difficult to obtain a con- trollable nucleation because the molecular bonds in III-V semiconductors are more covalent [1-4]. The synthesis of InP nanocrystals is the most extensively studied, but until now, InP nanocrystals synthesized by current chemical methods did not achieve the same quality as that of most II-VI semiconductor nanocrystals. Typical synthetic approaches for III-V nanocrystal quantum dots [NQDs] in a coordinating solvent are adaptations of the method for the II-VI group. However, * Correspondence: ykim@chungbuk.ac.kr; sjeong@kimm.re.kr † Contributed equally 1Nanomechanical Systems Research Division, Korea Institute of Machinery and Materials, Daejeon 305-343, Republic of Korea 2Department of Chemistry, Chungbuk National University, 52 Naesudong-ro, Heungdeok-gu, Cheongju, Chungbuk 361-763, Republic of Korea Full list of author information is available at the end of the article the common coordinating solvents and ligands and the similar precursors for the II-VI system do not work well for the synthesis of III-V NQDs. Both nucleation and crystal growth processes in these approaches needed long reaction times, all together 2 to 7 days, to yield a crystal- line particle [1-4]. Some researchers reported an approach using fatty acids and a mixture of fatty acids and amines and applying a non-coordinating solvent, 1- octadecene [ODE] [5-8]. This method provided a fast, controllable reaction and generated much higher-quality InP nanocrystals. In all cases, the use of the tris(tri- methylsilyl)phosphine [P(SiMe3)3] is mandatory, limiting the control of the synthesis of InP nanocrystals. Other than P(SiMe3)3, in situ-generated PH3 was introduced as a P precursor for InP synthesis by Peter Reiss’s group [9]. In the synthesis of high-quality InP or InP/ZnS NQDs in terms of size uniformity and crystallinity, a choice of an indium [In] precursor is flexible, but that of a phosphorus [P] precursor is quite limited, mostly relying on a highly expensive, toxic, flammable P source such as P(SiMe3)3. In this study, we designed and synthesized various organometallic P precursors with different functional © 2012 Joung et al; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.