Ternary IÀIIIÀVI AgInS 2 (AIS) semiconductor nanocrystals (NCs) with strong photoluminescence (PL) were synthesized using a one-pot reaction at low temperature. UVÀvis absorption and PL spectra red shifted as the AIS NCs grew. Both steady-state and time-resolved PL spectroscopies were used to investigate the influence of surface and intrinsic trap states on the PL behaviors of the prepared AIS NCs. PL lifetimes at different wavelengths in the full spectrum range were measured using a streak camera for each sample toward a systematic kinetic study. We found PL lifetime components that were short-lived from surface states and long-lived from intrinsic states. Surface trap emissions were wavelength-and size-dependent. Besides these PL studies, we report the first measurements using femtosecond transient absorption spectroscopy to investigate the exciton dynamics of the AIS NCs. Because of the abundant intrinsic trap states, these ternary AIS NCs have long-lived excitons, which may provide potential applications in photocatalysis and photovoltaics.

AgInS 2 −ZnS (AIZS) nanocrystals (NCs) were synthesized using a simple one-step approach by heating a Ag/ In/Zn/S solution to 210 °C providing highly tunable photoluminescence (PL). The incorporation of Zn even at low temperatures (∼150 °C) and the increased cation exchange of silver by zinc at higher temperatures strongly influence the optical properties of the resulting NCs. The correlation between synthesis parameters and resulting optical properties provided insights on the growth and stability of ternary and quaternary semiconductors. Systematic investigation with time-resolved spectroscopy showed distinguishable PL behaviors between developing and fully grown AIZS NCs. Attempts to coat as-prepared AgInS 2 NCs resulted in the same PL behavior as the one-step reaction product indicating that Zn readily exchanges with Ag ions even when not directly incorporated in the initial reaction mixture. Even with a low amount of zinc, the fully grown AIZS NCs showed improved PL QYs and single exponential decay behavior with long PL lifetimes. Control of the optical properties of these NCs makes them potentially useful for applications in photovoltaics and bioimaging particularly in light of their nontoxicity.