The passivation of organic light-emitting diodes (OLEDs) with Al2O3 films containing small amounts of N (Al2O3:N) was investigated by plasma-enhanced atomic layer deposition using a direct rf plasma with a short pulse time. Luminance—voltage and current density—voltage curves of an OLED passivated with a 300nm Al2O3:N film at 60°C remained unchanged compared to those of nonpassivated OLED and 96% of the initial luminance were maintained even after operating for 850h at 14mA∕cm2. The lifetime of an OLED with an 80°C Al2O3:N film was 650h, 6.2 times longer than that of a nonpassivated sample, although the luminance—voltage characteristics of the OLED were altered to a considerable extent.

Correlation across transmit antennas, in multiple antenna systems (MIMO), has been studied in various scenarios and has been shown to be detrimental or provide benefits depending on the particular system and underlying assumptions. In this paper, we investigate the effect of transmit correlation on the capacity of the Gaussian MIMO broadcast channel (BC), with a particular interest in the large-scale array (or massive MIMO) regime. To this end, we introduce a new type of diversity, referred to as transmit correlation diversity, which captures the fact that the channel vectors of different users may have different, and often nearly mutually orthogonal, large-scale channel eigen-directions. In particular, when taking the cost of downlink training properly into account, transmit correlation diversity can yield significant capacity gains in all regimes of interest. Our analysis shows that the system multiplexing gain can be increased by a factor up to M/r , where M is the number of antennas and r ≤ M is the common rank of the users transmit correlation matrices, with respect to standard schemes that are agnostic of the transmit correlation and treat the channels as if they were isotropically distributed. Thus, this new form of diversity reveals itself as a valuable "new resource" in multiuser communications. Index Terms

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