Three-dimensional assemblies built up by quantum dots in size-quantization regime: Band gap shifts due to size-distribution of cadmium selenide nanoparticles

•Optical absorption of 3D QD assemblies in size-quantization regime is modeled.•Band gap energy of the QD solid depends on the size-distribution of the nanoparticles.•QD solid samples with same 〈R〉 exhibit band gap shift depending on size distribution.•QD size distribution leads to large Urbach energies.

In the present study, it is predicted that the band gap energy of a three-dimensional quantum dot assembly exhibits a red shift when the dispersion of the crystal size distribution is enlarged, even at a fixed average value thereof. The effect is manifested when the size quantization regime in individual quantum dots constituting the assembly has been entered. Under the same conditions, the sub-band gap absorption tails are characterized with large Urbach energies, which could be one or two orders of magnitude larger than the value characteristic for the non-quantized case.

Graphical abstractBand gap shifts due to size-distribution of nanoparticles in 3D assemblies built up by quantum dots in size-quantization regime.Figure optionsDownload full-size imageDownload as PowerPoint slide