IOP PUBLISHING NANOTECHNOLOGY Nanotechnology 23 (2012) 075701 (9pp) doi:10.1088/0957-4484/23/7/075701 Nanocomposites based on highly luminescent nanocrystals and semiconducting conjugated polymer for inkjet printing E Binetti 1 ,2 , C Ingrosso 1 ,2,4 , M Striccoli 2 , P Cosma 1 ,2 , A Agostiano 1 ,2 , K Pataky 3 , J Brugger 3 and M L Curri 2 1 Chemistry Department, University ‘Aldo Moro’ of Bari, via Orabona 4, I-70126 Bari, Italy 2 CNR-IPCF Bari-Division c/o Chemistry Department, University ‘Aldo Moro’ of Bari, via Orabona 4, I-70126 Bari, Italy 3 Microsystems Laboratory, Ecole Polytechnique F´ ed´ erale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland E-mail: juergen.brugger@epfl.ch and lucia.curri@ba.ipcf.cnr.it Received 28 September 2011, in final form 30 November 2011 Published 20 January 2012 Online at stacks.iop.org/Nano/23/075701 Abstract In this work nanocomposites based on organic-capped semiconductor nanocrystals formed of a core of CdSe coated with a shell of ZnS (CdSe@ZnS), with different sizes, and a semiconducting conjugated polymer, namely poly[(9,9-dihexylfluoren-2,7-diyl)-alt- (2,5-dimethyl-1,4-phenylene)] (PF-DMB) have been investigated. The nanocomposites are prepared by mixing the pre-synthesized components in organic solvents, thereby assisting the dispersion of the organic-coated nano-objects in the polymer host. UV–vis steady state and time-resolved spectroscopy along with (photo)electrochemical techniques have been performed to characterize the obtained materials. The study shows that the embedded nanocrystals increase the PF-DMB stability against oxidation and, at the same time, extend the light harvesting capability to the visible spectral region, thus resulting in detectable photocurrent signals. The nanocomposites have been dispensed by means of a piezo-actuated inkjet system. Such inks present viscosity and surface tension properties well suited for stable and reliable drop-on-demand printing using an inkjet printer. The fabrication of arrays of single-color pixels made of the nanocomposites and micrometers in size has been performed. Confocal and atomic force microscopy have confirmed that inkjet-printed microstructures present the intrinsic emission properties of both the embedded nanocrystals and PF-DMB, resulting in a combined luminescence. Finally, the morphology of the printed pixels is influenced by the embedded nanofillers. S Online supplementary data available from stacks.iop.org/Nano/23/075701/mmedia (Some figures may appear in colour only in the online journal) 1. Introduction Nanometer-sized inorganic materials possess electronic properties which can be tuned as a function of their size 4 Present address: CNR-IMM Lecce, via Monteroni c/o Campus Ekotecne Palazzina A3, I-73100 Lecce, Italy. and shape, without varying chemical composition. This results in a variety of relevant optoelectronic applications, such as photoconversion, sensing and photocatalysis, as well as bioanalytical and biomedical purposes [1]. Among the diverse classes of nanostructured materials, nanocomposites formed of inorganic nanostructures and organic polymers 1 0957-4484/12/075701+09$33.00 c  2012 IOP Publishing Ltd Printed in the UK & the USA