Electroluminescent and photonic organic devices

OLEDs are devices which convert electricity into light through the process of electroluminescence. They are made by depositing an organic stack of tens of nanometers between two flat electrodes.  When an external voltage is applied to the device electrons are injected from the cathode and holes from the anode. Than they form excitons in the active layer which emit photons, with an energy equal to the energy gap of the active molecules. The structures are realized by doping the transport layers with electron-acceptor or electron-donating molecules (pin structure). Owing to pin structure we are able to finely tune the device without altering the electrical performances, thus allowing to work near the thermodynamic limit (applied voltage near the energy gap of emitting layer per unit charge) and to fabricate LED embedded into an electrically active micro-cavity. The research activities are focused on the following areas:

  1. Development of hybrid electroluminescent integrated devices
  2. Development of electroluminescent organic devices for industrial applications

Development of electroluminescent hybrid integrated devices

Electroluminescence is the process of generation of light by electrical injection of opposite carriers (electrons and holes) into a semiconductor. We have two main targets:

  1. Study of electroluminescence process into optical feedback

We are studying electroluminescence form organic compounds working in different light-matter coupling regimes: weak (WC), strong (SC) and ultrastrong (USC). In the WC the Fermi golden rule is changed by managing the photonic density of states (and the related Purcell effect) through the placement of the active material into an optical feedback (i.e. a dielctricmicrovavity).  We have exploited this effect to improve the efficiency of white OLEDs owing to the coupling of three metal microcavities. ITO-free devices with anefficiecy of 40lm/W in a full coupled microcavity diodes even on flexible substrateshave been developed.

SC and USC regimes are achieved when the dipoles exchange energy with the cavity at a rate larger than the losses from the cavity and the dephasing of the excitons. In this regime the energy of the cavity and the molecules change generating two hibrid states called polaritons. We work on the study of EL process from polaritons with the aim of developing polariton devices and Bose Einstein condensation under electrical injection.

 Development

a)       Study of electroluminescence process in perovskites(Pero-LEDs)

 

We realize LED based perovskite (Pero-LEDs) based on metal-halide perovskite materials, hybrid organic-inorganic compounds, which are recently making inroads in photovoltaics. These materials feature a unique combination of properties: they can be easily be fabricated, both from solution or thermally evaporated, on any substrate and have bright, colour tunable optical emission, like organics, but their electronic conduction properties resemble those of inorganic semiconductors, with large carrier mobility and diffusion lengths. Unfavorably, the important advantages offered by wet processability are accompanied by disconcerting limitations. It is well known, in fact, how the perovskite morphology, strongly depending on the growth conditions, severely impacts on the device performances, causing an intrinsic irreproducibility of the material chemical-physical properties. Therefore huge efforts have been devoted to the optimization of morphology and processing conditions, in particular by controlling the interactions of the material precursors in solution or with the substrate.A further constraint factor in the spin-coated devices is that the number of layers allowed are limited by their solubility in orthogonal solvents. The fabrication of hetero-structured devices may open ways to increase the number of layers allowing to decouple transport from optical characteristics, thus increasing the overall performances of the device, as already shown in small molecules based Organic LEDs (OLEDs). Vacuum-based deposition represents an excellent technique to achieve high-purity layers and potentially allows for a fine control over the stoichiometry and thickness of the perovskite films, thus their reproducibility. Recently we reported for the first time a fully vapor-deposited hetero-structure perovskite light emitting diode exploiting p-i-n technology, as the first step of an innovative approach to electroluminescent perovskite-based devices embedding electrical doping. The approach presented would potentially lead to a better control of the transport and electroluminescent properties of the device, as well as to the possibility of a wide industrial application. Acting on kinetic and thermodynamic conditions during the thermal deposition we study the impact of morphological and structural characteristics on the electro-optical behavior of the perovskite active layer. Several perovskites are explored in infrared and visible windows of electromagnetic spectrum. Analysis of optical characteristics at high current density both in cw and pulsed conditions is done to understand the bimolecular processes responsible for the light emission in perovskites and the aging of the device, which are fundamental to reach the population inversion and lasing. Indeed contrary to organics, in perovskite materials optical recombination is a bimolecular process, not requiring the formation of an exciton. Therefore the radiative efficiency increases with density, as the probability for electrons and holes to find a recombination partner increases, and becomes the dominant recombination channel, with the emission quantum yield approaching unity.

Development of electroluminescent organic devices for industrial applications

 

 Development2

 

Organic light-emitting diodes (OLEDs) are very promising type of technologies having a wide range of applications. In less than two decades, they have become a commercial reality in display technology (AMOLED). The development of large area white OLEDs (WOLEDs) for general lighting with an almost perfect Rendering Colour Index (CRI) near 100 and a  theoretical efficiency of  200 lum/W, is still a challenge.

More recently, Organic Light Emitting Field Effect Transistor (OLEFET) combining in a single device, the current modulation functions and electrical switching properties of a field effect transistor with light generation capabilities of an organic LED, have been investigated for display applications.

Different scientific approaches are followed to fabricate large area white OLED and efficient OLEFET for practical applications:

– The design and fabrication of a p-i-n microcavity structure (p-i-n MC-OLED) offers the possibility to optimize the outcoupling efficiency and improve the output luminance, through the amplification of the light emission next to the resonance wavelength of the single or coupled microcavity, without changing its electrical behaviour. (link to Ultra High Vacuum (UHV) Kurt. J. Lesker Cluster Tool facility)

– Study of supramolecular aggregates in organic semiconductors, particularly molecular crystal structures, and their integration in OLED devices, in order to minimize typical annihilation phenomena and improve device efficiency at high luminance. (link to Ultra High Vacuum (UHV) Kurt. J. Lesker Cluster Tool facility)

– Implementation of trilayer p-i-n ambipolar OLEFET structure. The doping level results crucial to the capability of emitting light, as well as to the electrical characteristics of the device. The hole and electron current profiles can be tailored in order to create simultaneous flows of opposite charges near and across the active layer, featuring light emission across the whole channel area. Device dimension range from 100um down to a few tens of nanometers. (link to Ultra High Vacuum (UHV) Kurt. J. Lesker Cluster Tool facility; nanofabrication facility)

Facilities & Labs

Device Lab @Lecce

People

Vincenzo_maioranoMaiorano

Vincenzo

CNR Tecnologist

Marco_pugliesePugliese

Marco

Associate PostDoc

Fabrizio_marianoFabrizio

Mariano

Associate PostDoc

Armando_GencoArmando

Genco

PHD Student

Sonia_caralloSonia

Carallo

CNR Technician

Marco MazzeoMarco

Mazzeo

Associate Resercher

Publications

  1. Genco , F. Mariano , S. Carallo , V. L. P. Guerra , S. Gambino , D. Simeone , A. Listorti, Silvia Colella , G. Gigli , and M. Mazzeo FullyVapor-DepositedHeterostructured Light-EmittingDiodeBased on Organo-Metal Halide Perovskite, Advanced Electronic Materials, 1500325 (2016)  DOI: 10.1002/aelm.201500325.
  2. Mazzeo, A. Genco, S.Gambino, D. Ballarini, F. Mangione, O. DI Stefano, S. patanè, S. Savasta, D. Sanvitto, G. Gigli, Ultrastrong light-matter coupling in electrically doped microcavity organic light emitting diodes, Applied Physics Letters Vol: 104,Issue:23 (2014)
  3. Accorsi, S. Carallo, M. Mazzeo, A. Genco, S. Gambino, G. Gigli; A colour tunable microcavity by weak-to-strong coupling regime transition through a light-switchable material Chemical communications Vol: 50,Issue:9(2014)

Other selected Publications

  1. Gambino, S.; Mazzeo M. Genco, Di Stefano, O; Savasta, S; Patane, S ; Ballarini, D ; Mangione, F ; Lerario, G; Sanvitto, D ; Gigli, G Exploring Light-MatterInteractionPhenomena under UltrastrongCoupling Regime, ACS PHOTONICS  (2014) Volume: 1   Issue: 10   Pages: 1042-1048
  2. Mazzeo, F. Mariano, A. Genco, S. Carallo, G. Gigli, High efficiency ITO-free flexible white organic light-emitting diodes based on multi-cavity technology, Organic electronics Vol: 14,Issue: 11 (2013)
  3. Maiorano, A.Bramanti, S.Carallo, R.Cingolani and G.Gigli, Organic light emitting field effect transistor based on ambipolar p-i-n layered structure Appl. Phys. Lett., 96, 133305 (2010)
  4. Mazzeo*, F. Della Sala, F. Mariano, G. Melcarne, S. D’Agostino, Y.Duan, R. Cingolani and G. Gigli Shaping white light through electroluminescent fully organic coupled-microcavities, Advanced Materials, 22, pg. 4696 (2010)

Patents

1) Organic light-emitting diode with microcavity including doped organic layers and fabrica-tion process thereof – , B.Dussert-Vidalet, M.Mazzeo, G.Gigli, M.BenKhalifa, F.DellaSala, V.Maiorano, F.MarianoUS 2011079772 (A1)  07/04/2011 ; N° US8969853 (B2) del 03/03/2015

Also published

  1. FR2926677 (A1) 24/07/2009 ; FR2926677 (B1) del 25/04/2014
  2. EP2235763 (A1) del 06/10/2010
  3. WO 2009090248 del 23/07/2009
  4. CA 2712251 23/07/2009
  5. KR 20110009080 (A) del 27/01/2011; KR101585018 (B1) del 13/01/2016
  6. CN 101978527 del 16/02/2011
  7. JP 2011510441 (A) del 31/03/2011 ; JP5594777 (B2) del 24/09/2014
  8. BRPI0906421 14/07/2015

2)Organic light emitting field effect transistor-V.Maiorano, G.Gigli, EP2545599 A1  16/01/2013

Also published

  1. IT RM20100107 13/09/2011
  2. WO 2011110664A1 15/09/2011

Project

MAAT: Molecular NAnotechnology for HeAlth and EnvironmenT ,  PON R&C 2007-2013 –  (2012-2015)

FT_WOLED: Flexible Transparent White Organic Light Emitting DeviceExecutive Programme for scientific and technological cooperation between Italy and China (2013-2015)

PHOEBUS: Plastic tecHnologies for the realization of Organic solar cells and high Efficiency Bright and Uniform Sources,  (2009-2011)

OLEDs for lighting, Project MIUR FAR 297 (2006-2009).

OLLA: Organic light emitting diodes for lighting, EUFP6 IP, (2005-2008)

Latest News

Technology Trasfer in Nanotechnology

Technology Transfer in Nanotechnology: Challenges and Opportunity

Lecce, 18/19 ottobre 2018

CNR NANOTEC c/o Campus Ecotekne

JRC in collaboration with the National Research Council (Cnr) is organising a workshop on Technology Transfer in Nanotechnology,

which will take place in CNR Nanotec (Lecce, Italy) on 18 and 19 October. This workshop is organised in the framework of the TTO-CIRCLE initiatives.   The aim of this event is to explore how technology transfer activities can be used as a mechanism to help EU industry, particularly Start-ups and SMEs, and Government in deploying and adopting Nano-technology. Practical examples will be presented to illustrate the potential of technology transfer in this area.   The workshop will gather technology providers, industry executives, technology transfer officers, policy makers and financial intermediaries to share experiences and lessons learned. One of the key objectives is to discuss policy implications at all levels that could help accelerating the adoption of Nanotechnology by the European manufacturing industry. More informations: https://ec.europa.eu/jrc/communities/community/european-tto-circle/event/technology-transfer-nanotechnology Download Locandina

Nanotechnology Transfer Day

26 Luglio 2018 - Lecce

CNR NANOTEC c/o Campus Ecotekne Siglato l’accordo lo scorso maggio tra CNR NANOTEC e Pairstech Capital Management, ha preso il via la collaborazione con PhD TT per la valutazione della ricerca

E’partita la collaborazione con PhD TT per la valorizzazione della ricerca sulla base dell’accordo siglato lo scorso Maggio tra CNR NANOTEC e Pairstech Capital Management, società di gestione patrimoniale che fornisce agli investitori istituzionali e privati un insieme di veicoli di investimento, al fine di valorizzare i risultati della ricerca svolta all'interno dell'Istituto.

Giovedì 19 Luglio dalle ore 11 alle ore 14 nella sede del CNR Nanotec di Lecce si è tenuto un incontro sul trasferimento tecnologico nel settore delle nanotecnologie applicate al settore biomedicale.

L’evento è stato organizzato dall’ufficio di Trasferimento Tecnologico del CNR Nanotec che ha inaugurato con questa giornata un ciclo di eventi mirato a presentare agli attori dell’ecosistema dell’innovazione nel settore delle nanotecnologie i vari modelli e alcune best practice di trasferimento tecnologico. In questa prima giornata il dott. Heber Verri e la dott.ssa Paola Urbani hanno presentato il nuovo modello di trasferimento tecnologico PhD TTãIndex Model.

PhD TT è una realtà italiana completamente indipendente specializzata in trasferimento tecnologico, è un acceleratore organizzato per il Go to Venture Practice, orientata al mondo delle Lifes Sciences.

PhD TT ha sviluppato un nuovo modello di trasferimento tecnologico: il PhD TT©INDEX MODEL dedicato alla generazione di valore dell'innovazione, focalizzato alla riduzione dei rischi delle opportunità di investimento a sostegno della ricerca.

I ricercatori intervengono attivamente nell'analisi iniziale di fattibilità e nella costituzione della futura società (start-up), con l'obiettivo di attrarre capitale di rischio utile a sostenere la fase del trasferimento tecnologico nella visione della "Research for go-to-market".

Il modello PhD TT nasce da un bisogno del mercato, quello di far dialogare due mondi estremamente diversi tra loro: il mondo della ricerca e il mondo degli investimenti.

PhD TT supporta tutte le attività in collaborazione con il TTO - CNR Nanotec con un team di lavoro esperto e grazie a un comitato scientifico-economico qualificato.

In occasione dell'evento del 19/7 u.s. al CNR Nanotec di Lecce, PHD TT ha presentato il proprio track record, dove si sono potuti valutare in dettaglio i casi di successo di intervento del PhD TT©INDEX MODEL.

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Disordered serendipity: a glassy path to discovery

A workshop in honour of Giorgio Parisi’s 70th birthday

September 19-21, 2018 - Roma

Sapienza University

With the occasion of celebrating Giorgio Parisi 70th birthday, the conference "Disordered serendipity: a glassy path to discovery" brings to Rome many among the world-leading experts in the field of complex systems. In order to properly represent the many fields of research where Giorgio Parisi gave a relevant contribution in his studies of disordered systems, the conference covers a broad spectrum of topics: from  fundamental and rigorous analysis of the statistical mechanics of disorder systems to applications in biology and computer science. These subjects are deeply interconnected since they are characterized by the presence of glassy behavior.

 

https://sites.google.com/site/disorderedserendipity/