Department of Materials Science and Engineering and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, 790-784, Republic of Korea.
Small. 2014 Sep 24;10(18):3678-84. doi: 10.1002/smll.201400392. Epub 2014 May 15.
Lattice distortion induced by residual stresses can alter electronic and mechanical properties of materials significantly. Herein, a novel way of the bandgap tuning in a quantum dot (QD) by lattice distortion is presented using 4-nm-sized CdS QDs grown on a TiO2 particle as an application example. The bandgap tuning (from 2.74 eV to 2.49 eV) of a CdS QD is achieved by suitably adjusting the degree of lattice distortion in a QD via the tensile residual stresses which arise from the difference in thermal expansion coefficients between CdS and TiO2. The idea of bandgap tuning is then applied to QD-sensitized solar cells, achieving ≈60% increase in the power conversion efficiency by controlling the degree of thermal residual stress. Since the present methodology is not limited to a specific QD system, it will potentially pave a way to unexplored quantum effects in various QD-based applications.
晶格畸变引起的残余应力会显著改变材料的电子和机械性能。本文提出了一种通过晶格畸变来调节量子点（QD）能带隙的新方法，并以 4nm 尺寸的 CdS QD 在 TiO2 颗粒上的生长为例进行了说明。通过适当调整 CdS 和 TiO2 之间热膨胀系数的差异引起的拉伸残余应力在 QD 中的晶格畸变程度，实现了 CdS QD 的能带隙调谐（从 2.74eV 到 2.49eV）。然后，将能带隙调谐的思想应用于 QD 敏化太阳能电池，通过控制热残余应力的程度，实现了约 60%的功率转换效率的提高。由于本方法不受特定 QD 体系的限制，因此它有可能为各种基于 QD 的应用中的未知量子效应开辟一条道路。
