Photonic band structure and emissive characteristics of MEH-PPV textured microcavities

A detailed comparison is made between the experimentally determined photonic band structure and the measured angle-dependent emission spectra of textured, metal-clad microcavities containing the light-emitting polymer MEH-PPV. Transmittivity measurements were made over a range of optical frequency and in-plane wavevector in order to obtain a detailed map of the dispersion of the waveguide modes supported by the textured cavities. Emission spectra were also recorded, for a large number of sample orientations, and are compared with the transmittivity maps. It is found that the band structure strongly influences the wavelength of the peaks in the emission spectra, and that the periodic texture leads to the generation of Bragg-scattered emission. The positions of these spectral peaks in both frequency and in-plane wavevector are found to agree very well with the positions of peak transmittivity of the cavities. The emission spectra also show clear evidence of the photonic band gaps formed by the periodic texture. The importance of these findings for light-emissive devices such as the light emitting diode is discussed.