Quantum-confined Stark effects inCdS1−xSexquantum dots

Quantum-confined Stark effects (QCSE’s) on exciton-decay dynamics in ${\mathrm{CdS}}_{0.31}$ ${\mathrm{Se}}_{0.69}$ semiconductor quantum dots (QD’s) embedded in a glass matrix have been studied by time-resolved photoluminescence emission spectroscopy under different electric fields up to 2.5×${10}^5$ V/cm. Under both conditions, in the absence or in the presence of an applied electric field, the exciton luminescence decay in QD’s is found to follow the stretched exponential function I(t)=${\mathit{I}}_0$exp(-${\mathit{At}}^{\mathrm{\beta }}$). The decay rate A and exponent β are found to vary linearly with the applied electric field, which can be accounted for by the field-induced reduction of the confined electron and hole wave-function overlap in QD’s. The QCSE observed in the QD’s is weaker than those observed in semiconductor quantum-well structures.