Semiconductor nanocrystals (NCs) have unique size and shape-dependent optical properties and therefore have wide applications in biological and energy applications. The stability of NCs, especially photostability under UV light radiation, is critical for their optical and electronic applications since UV light is generally required for the generation of excitons (i.e. excitation process) of the NCs. Under UV or room light radiation, two distinct processes on the surface of NCs can happen including 1) photo-annealing process (generally with short irradiation time) leading to increased photoluminescence (PL) quantum yield (QY); and 2) photo-oxidation process (generally with extended irradiation time) resulting in decreased PL QY due to the generation of surface defects as the result of sample degradation. Therefore, the limited photostability of NCs under UV light imposes restrictions on the wide applications of NCs.<br/><br/>In this study, we found the compressed PL of CdS and CdS/ZnS NCs due to photo-oxidation under UV light irradiation can be addressed by introducing a transition metal ion, Mn(II), as a dopant inside the NC lattice. The non-radiative relaxation of the surface trapped excitons can be largely re-activated by the tunable NC-to-dopant energy transfer. Specifically, it was found that surface oxidation of Mn doped CdS NCs (i.e. Mn:CdS) and Mn:CdS/ZnS core/shell NCs with thin shell (&lt; 2 ZnS monolayers) lead to the loss of surface Mn(II) and therefore decreased CdS-to-Mn(II) energy transfer, leading to a new CdS NC PL band in addition to the original Mn PL. However, for Mn:CdS/ZnS core/shell NCs with thick ZnS shell (shell thickness &gt; 2 ZnS monolayers), surface oxidation can lead to a thinner ZnS shell of the core/shell NCs (reflected by a blue shifted Mn PL) and more surface defects, which lead to a more efficient CdS-to-Mn(II) energy transfer and thus a stronger relative Mn PL is. Even through the opposite trend of NC-to-dopant energy transfer observed in Mn doped CdS NCs and thick ZnS shell passivated Mn:CdS/ZnS core/shell NCs, all these doped NCs have the tunable dual-band emissions under UV-light irradiation. The controlled emission color of the doped NCs by light irradiation provides a facile and efficient way to alter the optical properties of NCs.

Alteration of the optical properties of manganese-doped nanocrystals by UV light

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.