Electronic properties of Mn-phthalocyanine-C_(60) bulk heterojunctions: Combining photoemission and electron energy-loss spectroscopy

摘要

The electronic properties of co-evaporated mixtures (blends) of manganese phthalocyanine and the fullerene C_(60) (MnPc:C_(60)) have been studied as a function of the concentration of the two constituents using two supplementary electron spectroscopic methods, photoemission spectroscopy (PES) and electron energy-loss spectroscopy (EELS) in transmission. Our PES measurements provide a detailed picture of the electronic structure measured with different excitation energies as well as different mixing ratios between MnPc and C_(60). Besides a relative energy shift, the occupied electronic states of the two materials remain essentially unchanged. The observed energy level alignment is different compared to that of the related CuPc:C_(60) bulk heterojunction. Moreover, the results from our EELS investigations show that, despite the rather small interface interaction, the MnPc related electronic excitation spectrum changes significantly by admixing C_(60) to MnPc thin films.