Università degli Studi di Salerno Dip. Ing. Informazione ed Ing. Elettrica

1. S. Bellone, M. Petrosino, A. Rubino, P. Vacca Università degli Studi di SalernoDip. Ing. Informazione ed Ing. Elettrica Organic Electronics • Effect of ITO treatment on OLEDs performance • Realization and Characterization ofPolymeric Memories

2. Università degli Studi di Salerno Effect of ITO treatment on OLEDs performance Effect of ITO treatment on OLEDs performance Al 200 nm • The effect of various chemical–physical ITO surface treatments have been studied. • These treatments remove surface impurity, decrease surface roughness and increase ITO work–function. • Small molecules–ITO (NDP) interface and Polymeric–ITO (PF6) interface have been considered. • The hole-transporter layers depositing technique are been • thermic evaporation for small molecules • spin coating for polymeric molecules Electron transporter (ALQ3) 60 nm Hole transporter (NPD or PF6) 70 nm ITO 200 nm glass light This work is done in collaboration with Portici ENEA Research Center

3. Università degli Studi di Salerno Effect of ITO treatment on OLEDs performance OLEDs Energy diagrams ITO–NPD–Alq3–Al device ITO–PF6–Alq3–Al device An additional hole barrier is in NPD device A bigger hole anode barrier is in PF5 device

4. Università degli Studi di Salerno Effect of ITO treatment on OLEDs performance ITO chemical–physical propertiesfor various treatments Sheet resistance RMS roughness Surface energy Treatment Spikes Polarity (W/) (nm) (nm) (mJ/m2) Xp Piranha solution 10,03 63,08 0,58 4,50 10,70 11,13 9,40 46,60 2,60 UV ozone–HCl (12%) 0,51 42,36 0,31 14,50 HCl (12%) 12,31 3,10 1,80 10,44 Oxygen plasma 38,72 0,65 11,00 36,34 0,48 2,50 Annealing 200°C 10,33 11,90 24,90 34,40 10,00 3,00 0,52 UV ozone 24,70 HCl (6%) 12,50 12,46 33,31 0,44 Untreated 10,55 2,40 17,20 32,56 0,49

5. Università degli Studi di Salerno Effect of ITO treatment on OLEDs performance PF6–OLED Results • The best result is obtained with HCl–UV treatment with an increase of 60 in luminance • The device’s improvement is due to a better adhesion between polymer and substrate during spinning gotten by • increment of the apolar ITO surface energy because the solvent used is apolar • decrement of ITO surface roughness

6. Università degli Studi di Salerno Effect of ITO treatment on OLEDs performance NPD–OLED Results • The best result is obtained with HCl treatment with an increase of 100 in luminance • The device’s improvement is due to a better adhesion between evaporated organic moleculs and substrate during Joule–deposition gotten by • increment of the apolar ITO surface energy because NPD is an apolar molecule • increment of ITO surface roughness

7. Università degli Studi di Salerno Polymeric Memories Realization and Characterization of Polymeric Memories Al 200 nm New ad hoc polymers are used to realize organic memory cells. Organic layer is deposited usingspin–coating technique. The goal is to realize organic memory using low-cost technologies. To study transport and dynamic phenomena dummy device have been realized on p-type and n-type Si substrate. 150 nm Polymeric Active Layer Al on glassordoped–Si This research work is done in collaboration withDip. Ing. Chimica ed AlimentareUniversità di Salerno

8. Università degli Studi di Salerno Polymeric Memories Electric Bistability (I) N-Si / O2-Polymer / Al device The molecules show two states with different electrical conductivity This electrical bistability is imputable to conformational bistability To return from high conductivity state to low conductivity state, conformational switching is forced by high reverse electric field

9. Università degli Studi di Salerno Polymeric Memories Electric Bistability (II) Al / N-Polymer / Al device One order of difference in current between high conductive state and low conductive one is obtained