The performance stability of protocrystalline silicon is within 10% of the initial performance; its bandgap is slightly higher than that of amorphous silicon.
As its bandgap is around 1.5 eV, it can absorb most of the visible light.
Cadmium sulfide (or CdS) is a representative wide-bandgap II-VI semiconductor; its bandgap is 2.42 eV at room temperature.
By extrapolating (αhν 2 vs. hν plot to (αhν 2 = 0 (inset), its bandgap can be calculated.
Its bandgap energy was reported to be in the range from 1.65 to 1.8 eV [6 9].
Its bandgap (2.1 eV) is relatively narrower compared with that of NiO (3.5 eV).
A material can only absorb photons with energy higher than its bandgap, so optical bandgap holds the essence of light absorption and the absorptance depends straightly on optical bandgap.
A Kataura plot relates the nanotube diameter and its bandgap energies for all nanotubes in a diameter range.
Under the applied bias of 18 V, the potential gradient (drop) across the CdS NPs layers is greater than its bandgap (∼2.4 eV), large enough to form an electron hole pair, resulting in electroluminescence.
