Steering the Properties of MoOx Hole Transporting Layers in OPVs and OLEDs: Interface Morphology vs. Electronic Structure.

Wouter Marchal,Inge Verboven,Wouter Maes,Wim Deferme,Bert Conings,Ken Elen,An Hardy,Gilles Bonneux,Marlies Van Bael,Christopher De Dobbelaere,Jurgen Kesters,Hans Boyen,Boaz Moeremans

doi:10.3390/ma10020123

Wouter Marchal, Inge Verboven + Show 11 more

Open Access

https://doi.org/10.3390/ma10020123

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Journal: Materials	Publication Date: Jan 30, 2017
Citations: 6	License type: CC BY 4.0

Affiliation: Hasselt University, IMEC, Flanders Make (Belgium)

Abstract

The identification, fine-tuning, and process optimization of appropriate hole transporting layers (HTLs) for organic solar cells is indispensable for the production of efficient and sustainable functional devices. In this study, the optimization of a solution-processed molybdenum oxide (MoOx) layer fabricated from a combustion precursor is carried out via the introduction of zirconium and tin additives. The evaluation of the output characteristics of both organic photovoltaic (OPV) and organic light emitting diode (OLED) devices demonstrates the beneficial influence upon the addition of the Zr and Sn ions compared to the generic MoOx precursor. A dopant effect in which the heteroatoms and the molybdenum oxide form a chemical identity with fundamentally different structural properties could not be observed, as the additives do not affect the molybdenum oxide composition or electronic band structure. An improved surface roughness due to a reduced crystallinity was found to be a key parameter leading to the superior performance of the devices employing modified HTLs.

Highlights

Functional devices involving organic based active layers—such as organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs)—continue to receive considerable scientific attention due to their unique properties
Thermogravimetric analysis (TGA) results obtained on driedthree fine precursor(grain systems
Zirconium- and tin-containing molybdenum oxide (MoOx) layers were deposited via combustion solution processing, and both their composition and morphology were evaluated

Summary

Introduction

Functional devices involving organic based active layers—such as organic photovoltaics (OPVs) and organic light emitting diodes (OLEDs)—continue to receive considerable scientific attention due to their unique properties. The possibility of obtaining portable, light-weight, flexible devices produced in a cheap, scalable, and relatively eco-friendly way makes it a complementary technology next to silicon-based solar cells [1] and inorganic electro-luminescent materials [2,3]. Materials 2017, 10, 123 and optimization of new active materials [4,5,6], alternative device architectures [7], and progress in device fabrication in terms of efficiency, scalability, and simplicity (including solution processing) [8,9]. Various research groups have succeeded in introducing these interface layers via the solution-based processing approach [16,17,18]

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