Magnetism in Carbon Structures

We discuss different magnetic phenomena observed in carbon-based structures, in particular the diamagnetism, paramagnetism and ferromagnetism observed in graphite, disordered carbon, fullerenes and irradiated carbon structures.Comment: 6 pages, 3 figures, to be published in the proceedings of JEMS04, JMM

Nonlinear Transient Photovoltaic Response in Al/C60/Au Devices: Control of Polarity with Optical Bias

We report fast (nanosecond) transient photovoltaic response and steady-state photovoltage of rectifying Al/C60/Au sandwich devices. The transient photovoltage changes polarity at a critical light intensity, which can be varied and controlled by applying steady-state light as bias. This ability to change the polarity of the transient photovoltaic response and to control the intensity at which the polarity changes sign offers potential for use in applications in the area of fast nonlinear optoelectronic detectors. Applied Physics Letters is copyrighted by The American Institute of Physics

Altering Glass Transition of TPD thin Films with UV Light

N,N´-Bis(3-methylphenyl)-N,N’dyphenilbenzidine (TPD) is a hole-transport material used in electroluminescent devices whose glass transition temperature, Tg, depends on the film thickness.[1] For sufficiently thin films (d<30 nm), dewetting of amorphous TPD films deposited on a on fused silica or an ITO substrate occurs even at room temperature.[2] Following a brief report on increased thermal stability of UV irradiated TPD films,[3] we investigated the underlying mechanism responsible for it. From proton NMR and mass spectrometry measurements, coupled with morphology (AFM) and spectroscopy (UV-VIS) studies, we find that photo-excited TPD species react with oxygen in air. This leads to partially oxidized TPD films whose increased thermal stability we ascribe to stronger hydrogen bonding of photo-oxidized TPD species with hydrophilic substrates

Towards the mechanisam of stabilization of TPD thin films with UV light

Triphenyldiamine (TPD) or N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzdine is a well known hole-transporting material often used in electroluminescent devices. In bulk material glass transition temperature TTPDg ~ 60°C [1] is rather low and for sufficiently thin films (thickness d ~ 30 nm) deposited on a fused-silica substrate, dewetting occurs even at room temperature [2]. Morphological changes, which are often related to low Tg, lead to degradation of device performance in which thin film s are incorporated. That is why it is interesting to find a way to stabilize thin films. Following a brief report [3] on increased stability of UV irradiated TPD films, we focused on elucidating the underlying mechanism, since an explanation of chemical changes on molecular level has not yet been given. Thin amorphous TPD films were produced in physical vapor deposition (PVO) process on a fused silica or glass substrates. Immediately after evaporation one half of each sample was exposed to UV light under ambient conditions in order to compare effects of irradiation on a single film. Illuminated and non-illuminated areas of films are characterized using UV-visible spectroscopy and atomic force microscopy (AFM). Decrease in absorption bands intensity was observed after irradiation, indicating a chemical change in the sample. AFM study clearly shows that dewetting process at room temperature is stopped for irradiated samples thinner than 30nm. Illuminated samples remained stable even after few weeks of storage under ambient conditions and after 24h exposure to temperatures T > TTPDg. From proton nuclear magnetic resonance and mass spectrometry measurements, we find that photo-excited TPD reacts with oxygen from air, which leads to oxidation and hydroxylation of small amount of TPD molecules. W e conclude that increased thermal stability of irradiated films is due to hydrogen bonding among TPD molecules and molecules formed in hydroxylation process

Degradation of thin 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl films by UV light

We studied degradation of 4,4′-bis(2,2′diphenyl vinyl)-1,1′-biphenyl (DPVBi), well know OLED material. Thermally evaporated thin films of DPVBi were irradiated with UV light in ambient, vacuum and under different oxygen pressures. The cause of degradation is reaction between UV excited DPVBi molecules and oxygen, via formation of singlet oxygen or electron transfer from excited DPVBi to molecular oxygen. Reaction rates depend on oxygen concentration and UV light intensity. These reactions lead to formation of oxidized species as evidenced by ASAP and MALDI-TOF mass spectroscopy. Photoluminescence quenching has two parts. One part is reversible and may imply formation of charge transfer complexes and the other is irreversible, caused by formation of oxidized species. IR and absorption spectra are studied by Density Functional Theory and results compared with the experiment.SIXTEENTH ANNUAL CONFERENCE YUCOMAT 2014 Hunguest Hotel Sun Resort Herceg Novi, Montenegro, September 1-5, 201

Avelumab, an Anti-Programmed Death-Ligand 1 Antibody, In Patients With Refractory Metastatic Urothelial Carcinoma: Results From a Multicenter, Phase Ib Study

Purpose We assessed the safety and antitumor activity of avelumab, a fully human anti-programmed death-ligand 1 (PD-L1) IgG1 antibody, in patients with refractory metastatic urothelial carcinoma. Methods In this phase Ib, multicenter, expansion cohort, patients with urothelial carcinoma progressing after platinum-based chemotherapy and unselected for PD-L1 expression received avelumab 10 mg/kg intravenously every 2 weeks. The primary objectives were safety and tolerability. Secondary objectives included confirmed objective response rate (Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1), progression-free survival, overall survival (OS), and PD-L1-associated clinical activity. PD-L1 positivity was defined as expression by immunohistochemistry on ≥ 5% of tumor cells. Results Forty-four patients were treated with avelumab and followed for a median of 16.5 months (interquartile range, 15.8 to 16.7 months). The data cutoff was March 19, 2016. The most frequent treatment-related adverse events of any grade were fatigue/asthenia (31.8%), infusion-related reaction (20.5%), and nausea (11.4%). Grades 3 to 4 treatment-related adverse events occurred in three patients (6.8%) and included asthenia, AST elevation, creatine phosphokinase elevation, and decreased appetite. The confirmed objective response rate by independent central review was 18.2% (95% CI, 8.2% to 32.7%; five complete responses and three partial responses). The median duration of response was not reached (95% CI, 12.1 weeks to not estimable), and responses were ongoing in six patients (75.0%), including four of five complete responses. Seven of eight responding patients had PD-L1-positive tumors. The median progression-free survival was 11.6 weeks (95% CI, 6.1 to 17.4 weeks); the median OS was 13.7 months (95% CI, 8.5 months to not estimable), with a 12-month OS rate of 54.3% (95% CI, 37.9% to 68.1%). Conclusion Avelumab was well tolerated and associated with durable responses and prolonged survival in patients with refractory metastatic UC