Sulfide Quantum Dot Band-Gap Comparator

Sulfide nanocrystals — CdS, ZnS and PbS — are the workhorse quantum dots behind QLED displays, quantum-dot solar cells and infrared photodetectors, and every one of their optical properties starts from a single size-dependent equation. This simulator implements the Brus equation with the real bulk band gap, electron/hole effective masses and dielectric constant of each compound, so tuning a nanocrystal's radius genuinely shifts its computed band gap and recolors a 3D size-ladder of quantum dots plus a glowing "hero" nanocrystal to match the resulting emission wavelength. Switching between CdS, ZnS and PbS shows why the same confinement physics produces wildly different real-world behavior: CdS tunes across the visible spectrum, ZnS stays locked in the UV, and PbS — with its huge exciton Bohr radius — can be dragged from the infrared all the way into visible light.