Study of PbS Quantum Dots (QDs) and Proposing Pb@PbS-QD@CdSe for New Generation of LEDs

PbS quantum dots (PbS-QDs) are one of the best candidates in new generation of LEDs. When the PbS-QDs are exposed to light spectrum, the electrons in the valence band (VB) are excited to the conduction band (CB). The excited electrons then return from the CB to the VB and release extra energy by emitting light. The return of electrons to the VB makes it possible to repeat the light absorption-emission circle. If the size of the PbS-QDs is smaller than the Bohr magneton radius (PMR), the probability of the electron return to the VB decreases. This leads to phenomena named quantum dot blinking (QDB) in light-emitting diodes (LEDs), which is not desirable. In this research, a new approach has been proposed in which the addition of a metal substrate for PbS-QDs with a semiconductor shell with a suitable band edge could increase PbS-QDs efficiency in QD-LEDs and overcome the QDB problem.