Published January 1, 2019
| Version v1
Journal article
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Ultrathin Highly Luminescent Two-Monolayer Colloidal CdSe Nanoplatelets
Creators
- 1. Bilkent Univ, Dept Elect & Elect Engn, Dept Phys, UNAM Inst Mat Sci & Nanotechnol, TR-06800 Ankara, Turkey
- 2. Nanyang Technol Univ, Sch Elect & Elect Engn, Ctr Optoelect & Biophoton, Optimus, 50 Nanyang Ave, Singapore 639798, Singapore
- 3. Nanyang Technol Univ, Luminous Ctr Excellence Semicond Lighting & Displ, Sch Elect & Elect Engn, 50 Nanyang Ave, Singapore 639798, Singapore
- 4. Nanyang Technol Univ, Sch Phys & Math Sci, Div Phys & Appl Phys, 21 Nanyang Link, Singapore 639798, Singapore
Description
Surface effects in atomically flat colloidal CdSe nanoplatelets (NLPs) are significantly and increasingly important with their thickness being reduced to subnanometer level, generating strong surface related deep trap photoluminescence emission alongside the bandedge emission. Herein, colloidal synthesis of highly luminescent two-monolayer (2ML) CdSe NPLs and a systematic investigation of carrier dynamics in these NPLs exhibiting broad photoluminescence emission covering the visible region with quantum yields reaching 90% in solution and 85% in a polymer matrix is shown. The astonishingly efficient Stokes-shifted broadband photoluminescence (PL) emission with a lifetime of approximate to 100 ns and the extremely short PL lifetime of around 0.16 ns at the bandedge signify the participation of radiative midgap surface centers in the recombination process associated with the underpassivated Se sites. Also, a proof-of-concept hybrid LED employing 2ML CdSe NPLs is developed as color converters, which exhibits luminous efficacy reaching 300 lm W-opt(-1). The intrinsic absorption of the 2ML CdSe NPLs (approximate to 2.15 x 10(6) cm(-1)) reported in this study is significantly larger than that of CdSe quantum dots (approximate to 2.8 x 10(5) cm(-1)) at their first exciton signifying the presence of giant oscillator strength and hence making them favorable candidates for next-generation light-emitting and light-harvesting applications.
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