The effect of multilayer barrier materials on the lifetime of organic photovoltaic cells has been investigated. For thin film encapsulated cells a protective layer was used to prevent damage during barrier layer deposition. No post deposition effects developed after dry box storage. In accelerated temperature and humidity lifetime testing the degradation of the encapsulated cells can be related to the loss of effective cell area. An extrapolation of the lifetime at room conditions has been quantitatively determined by comparing the cell degradation with the loss of Ca in a Ca-oxidation test. The results indicate a barrier permeation rate of 10-4 gr/[m2* day] for these samples, corresponding to a lifetime of greater than 5000 hours. Routes to improvement of the OPV cell lifetime are discussed.
Thin film barrier coatings for protecting Organic Light Emitting Diode (OLED) displays against the environment are extremely difficult to fabricate. The coatings must have extremely low water/oxygen permeability, no defects, cover several microns of topography, and be applied at temperatures below 100°C in a process that does not compromise the performance of the display. Vitex Systems has succeeded in depositing such coatings using an organic/inorganic, thin film multilayer structure termed Barix encapsulation. In this paper results on encapsulation of OLED test pixels and passive matrix displays will be shown. Lifetime and permeability tests conducted at high temperature and humidity demonstrate that this thin film coating can meet the necessary performance requirements for commercial OLED displays. Processing parameters, layer architecture and manufacturing techniques are analyzed and discussed. Thin film encapsulated displays are used to demonstrate the utility of the encapsulation technique.
The mass spectral fragmentation of l-tryptophan has been investigated as a function of desorption technique and photoionization method using 7 keV Ar+ static sputtering, 355 nm pulsed laser-induced desorption, and thermal desorption at 150 to 200 degree(s)C in conjunction with 118 nm (10.49 eV), 266 nm (4.66 eV), and 355 nm (3.50 eV) laser positionization. In addition, ion-stimulated desorption of neutrals has been compared with positive secondary ion data. Molecular fragmentation is dominated by the internal energy contribution of the desorption process rather than photoionization method; fragmentation is maximal with ion-stimulated desorption and minimal with thermal desorption. Furthermore, single-photon ionization with 118 nm generally results in less fragmentation than multiphoton ionization (MPI). Finally, the effect of laser pulse width on the 266 nm MPI of thermally-desorbed neutral species has been explored. The use of 35 ps rather than 5 ns laser pulses at 266 nm has been explored. The use of 35 ps rather than 5 ns laser pulses at 266 nm has been found to cause a decrease in the molecular fragmentation of l-tryptophan. These results have implications for the surface analysis of labile organic compounds.