Department of Chemical Engineering and §Division of Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
ACS Appl Mater Interfaces. 2011 Aug;3(8):3033-41. doi: 10.1021/am200541p. Epub 2011 Aug 3.
Surface passivation of semiconductor nanocrystals (NCs) is critical in enabling their utilization in novel optoelectronic devices, solar cells, and biological and chemical sensors. Compared to the extensively used liquid-phase NC synthesis and passivation techniques, gas-phase routes provide the unique opportunity for in situ passivation of semiconductor NCs. Herein, we present a method for in situ gas-phase organic functionalization of plasma-synthesized, H-terminated silicon (Si) NCs. Using real-time in situ attenuated total reflection Fourier transform IR spectroscopy, we have studied the surface reactions during hydrosilylation of Si NCs at 160 °C. First, we show that, during gas-phase hydrosilylation of Si NCs using styrene (1-alkene) and acetylene (alkyne), the reaction pathways of the alkenes and alkynes chemisorbing onto surface SiH(x) (x = 1-3) species are different. Second, utilizing this difference in reactivity, we demonstrate a novel pathway to enhance the surface ligand passivation of Si NCs via in situ gas-phase hydrosilylation using the combination of a short-chain alkyne (acetylene) and a long-chain 1-alkene (styrene). The quality of surface passivation is further validated through IR and photoluminescence measurements of Si NCs exposed to air.
半导体纳米晶体（NCs）的表面钝化对于实现其在新型光电设备、太阳能电池以及生物和化学传感器中的应用至关重要。与广泛应用的液相 NC 合成和钝化技术相比，气相途径为半导体 NC 的原位钝化提供了独特的机会。在此，我们提出了一种用于等离子体制备的、氢终止的硅（Si）NCs 的原位气相有机官能化方法。使用实时原位衰减全反射傅里叶变换红外光谱，我们研究了在 160°C 下 Si NCs 的硅氢化反应过程中的表面反应。首先，我们表明，在使用苯乙烯（1-烯烃）和乙炔（炔烃）的 Si NCs 的气相硅氢化过程中，烯烃和炔烃化学吸附到表面 SiH(x)（x = 1-3）物种上的反应途径是不同的。其次，利用这种反应性的差异，我们通过使用短链炔烃（乙炔）和长链 1-烯烃（苯乙烯）的组合，展示了一种通过原位气相硅氢化来增强 Si NCs 表面配体钝化的新途径。通过将 Si NCs 暴露于空气中进行的红外和光致发光测量进一步验证了表面钝化的质量。
