Electronic properties of Mn-Phthalocyanine - C$_{60}$ bulk heterojunctions: combining photoemission and electron energy-loss spectroscopy

TL;DR

This study investigates the electronic properties of Mn-Phthalocyanine and C60 blends using photoemission and electron energy-loss spectroscopy, revealing how mixing ratios affect electronic structure and excitations.

Contribution

It provides detailed electronic structure analysis of MnPc:C60 heterojunctions and compares energy level alignment with CuPc:C60 systems, highlighting the effects of mixing ratios.

Findings

Occupied electronic states remain largely unchanged with mixing.

Energy level alignment differs from CuPc:C60 heterojunctions.

Electronic excitation spectrum of MnPc is significantly altered by C60 admixture.

Abstract

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) as well as 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 of the rather small interface interaction the MnPc related electronic excitation spectrum changes significantly by admixing C$_{60}$ to MnPc thin films.