Ultrafast exciton dynamics in colloidal aluminum phosphide nanocrystals

► Long living emissive (1 ns) excitons observed in colloidal AlP nanoparticles. ► Strong red-shifted and broad emission spectrum is observed. ► Reconstructed nonlinear spectrum shows a macroscopic gain can be induced. ► Long living (8 ns) dark population coexists with short living (1.2 ns) bright population.