Observation of long-lived excitons in InAs quantum dots under thermal redistribution temperature

► We study the temperature-dependent time-resolved photoluminescence of InAs QDs. ► Surprisingly long decay time is observed before the thermal redistribution. ► The anomalous behavior is suppressed by the high excitation power. ► The spin-flip between dark and bright states gives quantitative explanation. ► Unbalanced initial population between dark and bright states is odd but necessary.