Question

1) If the reaction continues for a long time, i.e, the quantum dots grow increasingly large, how do thier optical properties evolve accordingly?

2) why are quantum dots emission peaks very broad?

Answer 1

1.In semiconductors,an electron excited from the valence to the conduction band ,when this electron comes back to ground state it emits energy as light this is called fluorescence.

the emitted energy depends on the quantum dot's size, both absorption and fluorescence can be identify by changing the size of the quantum dot. The larger the dot, it becomes more and more redder (lower energy) absorption and fluorescence spectrum. Conversely, smaller dots absorb and emit blue (higher energy) light

2.here, the concept of Stokes shift comes, it is the difference between quantum dot's peak excitation (absorption) and the peak emission wave- lengths . The energy associated with emission is typically lower than the excitation light .therefore emission peak is broad