Probing the Fluorescence Dipoles of Single Cubic CdSe/CdS Nanoplatelets with Vertical or Horizontal Orientations

• Published in: ACS photonics Vol. 5; no. 5; pp. 1994 - 1999
• Main Authors: Feng, Fu, NGuyen, Loan Thu, Nasilowski, Michel, Nadal, Brice, Dubertret, Benoît, Maître, Agnès, Coolen, Laurent
• Format: Journal Article
• Language: English
• Published: American Chemical Society 16-05-2018
• Subjects: Chemical Sciences; single fluorescent emitter; radiation dipole; emission polarization; nanoplatelet; radiation pattern
• ISSN: 2330-4022; 2330-4022
• DOI: 10.1021/acsphotonics.7b01475

Measuring the orientation of a single fluorescent nanoemitter and obtaining emitters with a desired orientation is of highest importance for nanophotonics, especially in plasmonics where an emitting dipole close to a metallic surface will couple efficiently to plasmonic modes only if it is deposited vertically. Control of the orientation of a nano-object remains a challenge. Achieving vertical orientation, or having an information on the dipole orientation are key steps for efficient plasmonic excitation. We consider here cubic-shaped nanoplatelets with a thin CdSe core sandwiched in a thick CdS shell. By a combination of polarization measurement and radiation pattern Fourier analysis, we show that each single platelet behaves with excellent precision as a 2D dipole (sum of 2 orthogonal incoherent dipoles) and having only two possible orientations: either they lie horizontally on the substrate or they stand vertically on the edge. The cubic shape allows some platelets to deposit vertically so that they present a deterministic vertical dipole component.