The active layer analysis of interpenetrating heterojunction organic thin-film solar cells by X-ray photoelectron spectroscopy (XPS) has been studied. The interpenetrating heterojunction structure based on poly(3-hexylthiophene) (P3HT) and fullerene (C 60) could be fabricated by spin-coating P3HT onto a deposited C 60 film. The composition ratios of P3HT and C 60 in the interpenetrating heterojunction active layer in the depth direction and the interface morphology between the P3HT and C 60 layers have been clarified by XPS with argon ion etching and scanning electron microscopy. It has been found that the donor-acceptor interface of the interpenetrating heterojunction active layer is formed by the rod-shaped C 60 particles with a width of approximately 100 nm and C 60 grains with a size of 10-50 nm.

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Inorganic electroluminescence (EL) devices have attracted attention because of their application in low-power-consumption displays. However, the operating voltage of inorganic EL devices is very high. We have investigated AlBNO films as host materials of the luminescence layer to lower the operating voltage. Moreover, the investigation used Tb as the luminescence center because Tb3+ ions show green luminescence that has a high luminous coefficient. Tb-doped AlBNO films were deposited by RF magnetron sputtering. Cathodoluminescence and photoluminescence show the luminescence due to f–f transition of Tb3+ ions. The luminescence can be attributed to both the energy transfer from the host material to the Tb3+ ions and the direct excitation of Tb3+ ions. In addition, we achieved a drastic increase in the luminescence by an annealing treatment due to an increase in Tb3+ ions and the homogeneous dispersion of Tb atoms. Therefore, AlBNO films could be used for inorganic EL devices.

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