Excitation of thin cyanine films via energy transfer from Si substrate

Abstract

Energy transfer from an inorganic substrate to a cyanine molecule thin film has been investigated as an excitation method for organic luminescent devices. Cyanine molecule thin films were fabricated on a Si substrate by layer-by-layer assembly and were excited from the back side of the substrate to observe the luminescence. The luminescence intensity depends on the excitation power and excitation energy. Moreover, the dependence of the luminescence intensity on the excitation energy clearly shows a profile similar to the absorption spectrum of Si. These results indicate that luminescence is not due to the direct optical excitation of cyanine by the light transmitted through the substrate but due to the energy transfer from the photoexcited carriers in the substrate. Our results demonstrate that such energy transfer can be used to excite organic molecules on inorganic substrates without energy matching between the electrodes and luminescent materials.