Enhanced Valley Splitting of Exciton Emission in Colloidal
PbSe Quantum Dots When the Interdot Distance Coincides with Onset
of Förster Resonance Energy Transfer
posted on 2021-03-23, 16:50authored byTakahisa Omata, Hiroshi Asano, Masahiro Sakai, Yoshikazu Terai, Masao Kita
Photoluminescence
(PL) emission of colloidal PbSe/CdSe core/shell
quantum dots (QDs, CdSe shell thickness: 0.2 nm) at the lowest exciton
state was investigated at room temperature and varying inter-QD distance
(L = 7–240 nm) by changing the QD concentration.
A distinct enhancement of the valley splitting of PbSe QDs was observed
upon reducing L. Simultaneously, there was a redshift
in the emission due to Förster resonance energy transfer (FRET),
when the L value was still sufficiently large (7
nm ≤ L ≤ 50 nm) so that the wave functions
of different QDs do not overlap. The enhanced valley splitting under
no apparent external field is quite interesting as a method to control
the valley splitting. The electronic coupling leading to FRET may
enhance the valley splitting, because it occurs in an identical range
of L.