Optical properties of Fabry–Perot microcavity with organic light emitting materials

We investigated the optical properties of the tris(8-hydroxyquinoline)aluminum (Alq3) organic film with Fabry–Perot microcavity by measuring photoluminescence (PL) and transmittance. We have simulated the phase change on reflection as a function of wavelength. The Fabry–Perot microcavity structures were designed according to the simulation results and the resonant wavelength corresponding to the maximum of PL spectrum of a bare Alq3 film. These structures were fabricated in three types of microcavities, such as type A [air|metal|Alq3|metal|glass], type B [air|dielectric|Alq3|dielectric|glass], and type C [air|metal|Alq3|dielectric|glass]. A bare Alq3 layer on glass, [air|Alq3|glass], showed a PL peak around 514 nm and its full width at half maximum (FWHM) was about 80 nm. The broad FWHM of the bare Alq3 film was reduced to 15–27.5, 7–10.5 and 16–16.6 nm for three types by cavity effects. Also, the control of the resonant wavelength can be achieved by the spacer length as well as the phase change on reflection on mirror.