Percolation limited emission intensity from upconverting NaYF4:Yb3+, Er3+ nanocrystals – a single nanocrystal optical study. Issue 45 (12th November 2018)

• Record Type: Journal Article
• Authors: Podhorodecki, A.; Krajnik, B.; Golacki, L. W.; Kostiv, U.; Pawlik, G.; Kaczmarek, M.; Horák, D.
• Is Part Of: Nanoscale. Volume 10:Issue 45(2018)
• Page Start: 21186
• Page End: 21196
• Publication Date: 2018-11-12
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c8nr05961f
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : Based on single nanocrystals optical studies and numerical simulations, the optimal Yb 3+ and Er 3+ concentration in NaYF4 upconverting nanocrystals has been explained as due to percolation threshold and lost of excitation energy at NCs surface. Abstract : Upconverting nanocrystals (UCNC) have recently been subjected to intensive investigation due to their interesting optical properties and high potential for practical applications. Despite the level of attention paid to these materials, very low quantum yield is still an important issue. In order to break through this limitation, understanding of the emission intensity limitation is crucial. In this paper, we investigate the influence of percolation phenomena on the limitation of the emission intensity from NaYF4 :Yb 3+, Er 3+ nanocrystals. We propose a numerical model and support this experimentally at the single nanocrystal level, explaining the influence of Yb 3+ concentration on the optical properties of UCNC. Moreover, based on the experimental and numerical results, we explain the existence of the optimal Yb 3+ concentration in the core architecture often reported in the literature. All the measurements have been performed using a custom-built wide-field fluorescence microscope to analyze the emission from hundreds of single nanocrystals and thus make analysis independent of UCNC concentration.