量子点（英语：Quantum Dot）是在把激子在三个空间方向上束缚住的半导体纳米结构。这种约束可以归结于静电势（由外部的电极，掺杂，应变，杂质产生），两种不同半导体材料的界面（例如：在自组量子点中），半导体的表面（例如：半导体纳米晶体），或者以上三者的结合。量子点具有分离的量子化的能谱。所对应的波函数在空间上位于量子点中，但延伸于数个晶格周期中。一个量子点具有少量的（1-100个）整数个的电子、电洞或电子电洞对，即其所带的电量是元电荷的整数倍。

Quantum dots (QD) are nanoscale semiconductor devices that tightly confine either electrons or electron holes in all three spatial dimensions. They can be made via several possible routes including colloidal synthesis, plasma synthesis, or mechanical fabrication. The term “quantum dot” was coined by Mark Reed in 1988; however, they were first discovered in a glass matrix by Alexey Ekimov in 1981 and in colloidal solutions by Louis E. Brus in 1985. The electronic properties of the quantum dots fall between those of bulk semiconductors and those of discrete molecules of comparable size, and optoelectronic properties such as band gap, can be tuned as a function of particle size and shape for a given composition. For example, the photoluminescence of a QD can be manipulated to specific wavelengths by controlling particle diameter. Larger QDs (radius of 5-6 nm, for example) emit longer wavelengths resulting in emission colors such as orange or red. Smaller QDs (radius of 2-3 nm, for example) emit shorter wavelengths resulting in colors like blue and green, although the specific colors and sizes vary depending on the exact composition of the QD.