Room temperature luminescence in CuI/AgI quantum dots

Role of Self-Trapped Excitons in the Broadband Emission of Lead-Free Perovskite-Inspired Cu2AgBiI6

“…Apart from Cu 2 BiI 5 or Ag–Bi–I and Cu–Ag–I-based impurities, very small quantities of AgI or BiI 3 may coexist with CABI. While the AgI is nonemissive, , the PLE spectrum and TA dynamics of BiI 3 (Figure S3) suggest that it is not the source of emission. We employed fluorescence lifetime imaging microscopy (FLIM) to examine the coexistence of luminescence impurities within CABI .…”

“…This can be supported by the observations of Annadi et al on Ag x Cu 1– x I alloy samples, in which Ag and I defect levels act as two emitting states with distinct energy positions . In another study, Wei et al proposed radiative recombination between the trapped carriers in interstitial silver ion vacancies in the silver-rich regions and the vacancy-compensated ions, leading to a broad emission covering 500–900 nm for CuI/AgI glass system . Further, the strong covalent nature of Ag–I bonds , might inhibit the self-trapping through the Ag–I polyhedral distortion, in contrast to the facile STE formation through the distorted AgCl 6 in Cs 2 AgInCl 6 and AgCl crystals .…”

“…In another study, Wei et al proposed radiative recombination between the trapped carriers in interstitial silver ion vacancies in the silver-rich regions and the vacancy-compensated ions, leading to a broad emission covering 500–900 nm for CuI/AgI glass system . Further, the strong covalent nature of Ag–I bonds , might inhibit the self-trapping through the Ag–I polyhedral distortion, in contrast to the facile STE formation through the distorted AgCl 6 in Cs 2 AgInCl 6 and AgCl crystals . The broad emission of Cu 2 Ag 2 I 4 :Bi arising from dual emissive trapped states could be a consequence of more extrinsic, that is, defect/vacancy-mediated than intrinsic self-trapping. ,,, The influence of the lattice defects on local structural perturbation in the excited state can be further verified using ultrafast X-ray absorption techniques .…”