A.N. Safonov

Modification of polymer light emission by lateral microstructure

We report the use of wavelength-scale microstructure to control the intensity, spectrum and polarisation of light-emission from thin polymer films. It is shown that periodic corrugation of the emissive layer can substantially increase the efficiency of light-emission. Detailed photoluminescence (PL) studies of the angle dependence of the emission together with theoretical modelling show that the observed emission enhancement is associated with Bragg-scattering of waveguided light out of the polymer layer. The application of this approach to increase the efficiency of a light-emitting diode (LED) is demonstrated.

Optically active hydrogen dimers in silicon

Abstract First-principles calculations are used to explore the structure and properties of several defects which are prominent luminescent centers in Si. The trigonal defects B 41 and B 71 1 , which are known to contain two hydrogen atoms in equivalent and inequivalent sites, respectively, are attributed to a hexavacancy containing two H atoms in different configurations. It is suggested that the J luminescence centers arises from a stable hexavacancy without hydrogen atoms.