An understanding and control of metal–polymer interfaces is important for the development of conjugated polymer–based light‐emitting diodes. For example, do interactions at the interface modify the ...geometric structure and electronic properties of the conjugated system? This question is addressed here by a combined theoretical and experimental approach that has allowed the vibrational properties—which are intimately related to molecular structure and bonding—of interfaces between aluminum and oligothiophenes to be determined.
Light emission from organic semiconductors is attracting considerable attention nowadays. In conventional organic light-emitting diodes (OLED) the optical emission is governed by the radiative decay ...of singlet excitons, while triplet excitons can lead to some delayed fluorescence or phosphorescence. Controlling the spin statistics by injecting and transporting carriers with defined spin orientation can amplify a chosen electronic transition increasing the device efficiency or changing the emission spectral band. Electro-optical characterizations of OLEDs based on Alq3 electroluminescent material are presented for both normal and spin polarized electrode configurations. Epitaxial thin films of the manganite La/sub 0.7/Sr/sub 0.3/MnO/sub 3/ were used as spin polarized (SP) hole injector, while iron and cobalt films were used as SP electron injecting electrode. Our results demonstrate the suitability of ferromagnetic metals as electrodes in OLED opening new possibilities for OLED operation.
In this communication, we present IR-excited Raman scattering of single crystals of PrBa
2Cu
3O
7−y. In contrast with Raman scattering excited in the visible, we find the presence of two different ...Raman modes with energy around 500 cm
−1. Comparison with visible excitation and with the band associated with the apex oxygen local modes in low-oxygen Pr
xY
1−xBa
2Cu
3O
6+y indicates that there are two separate vibrational modes associated with the apex oxygen position in the high oxygen phase of PrBa
2Cu
3O
7−y. We interpret this as due to the existence of two different sites for apex oxygen atoms and in terms of polaronic states in the chain sites.
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