Electronic Structure of C60/Zinc Phthalocyanine/V₂O₅ Interfaces Studied Using Photoemission Spectroscopy for Organic Photovoltaic Applications.

Chang Jin Lim,Yeonjin Yi,Min Su Kim,Mann-Ho Cho,Hyunbok Lee,Jeong Hwa Han,Soohaeng Cho,Sang Wan Cho,Min Gyu Park

doi:10.3390/molecules23020449

Chang Jin Lim, Yeonjin Yi + Show 7 more

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https://doi.org/10.3390/molecules23020449

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Abstract

The interfacial electronic structures of a bilayer of fullerene (C60) and zinc phthalocyanine (ZnPc) grown on vanadium pentoxide (V2O5) thin films deposited using radio frequency sputtering under various conditions were studied using X-ray and ultraviolet photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital (HOMO) level of the ZnPc layer and the lowest unoccupied molecular orbital (LUMO) level of the C60 layer was determined and compared with that grown on an indium tin oxide (ITO) substrate. The energy difference of a heterojunction on all V2O5 was found to be 1.3~1.4 eV, while that on ITO was 1.1 eV. This difference could be due to the higher binding energy of the HOMO of ZnPc on V2O5 than that on ITO regardless of work functions of the substrates. We also determined the complete energy level diagrams of C60/ZnPc on V2O5 and ITO.

Highlights

Organic photovoltaics (OPVs) have received increasing attention over the past few years due to their potential as a renewable, cheap, and economical source of power [1,2,3,4,5,6]
V2 O5 #1 sample was grown in an Ar atmosphere for 5 min, and the V2 O5 #2 sample was grown in an
The V2 O5 #3 sample was deposited in an Ar:O2 atmosphere for 20 min

Summary

Introduction

Organic photovoltaics (OPVs) have received increasing attention over the past few years due to their potential as a renewable, cheap, and economical source of power [1,2,3,4,5,6]. Recent efforts have been made to improve charge transport and collection at the electrodes. The use of transition metal oxides as a transparent electrode has attracted considerable interest [7]. The surface chemistry of ITO is difficult to control [8] and ITO has become approximately 10 times more expensive over the past few years due to diminishing indium resources [9]. Transition metal oxides are believed to prevent unwanted chemical reactions between transparent electrodes and an optically active organic layer [11,12,13].

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