Slot-Die Coating of Double Polymer Layers for the Fabrication of Organic Light Emitting Diodes.

Amruth C,James Kingsley,Beata Luszczynska,Jonathan Griffin,Nicholas Scarratt,Jacek Ulanski,Marco Colella

doi:10.3390/mi10010053

Abstract

This study presents the slot-die coating process of two layers of organic materials for the fabrication of organic light emitting diodes (OLEDs). Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which is commonly used in OLEDs and in organic photovoltaic devices as the hole injection layer (HIL), has been deposited via slot-die coating. Uniform films of PEDOT:PSS were obtained after optimizing the slot-die processing parameters: substrate temperature, coating speed, and ink flow rate. The film quality was examined using optical microscopy, profilometry, and atomic force microscopy. Further, poly(9,9-dioctylfluorene) (F8) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), a well know polymer blend F8:F8BT, which is used as an emissive layer in OLEDs, has been slot-die coated. The optoelectronic properties of the slot-die coated F8:F8BT films were examined by means of photoluminescence (PL) and electroluminescence (EL) studies. The fabricated OLEDs, consisting of slot-die coated PEDOT:PSS and F8:F8BT films, were characterized to record the brightness and current efficiency.

Highlights

The manufacturing of organic electronic devices using solution-based deposition techniques, such as coating and printing, have drawn extensive attention because they can be upgraded to industrial scale [1,2,3,4,5]
Many multilayer devices, including organic light emitting diodes (OLEDs) [10], photovoltaics [11], transistors [12], and sensors [13] have been fabricated by partially using this technique for the deposition of some layers
The film morphology was examined under an optical microscope and using profilometry

Summary

Introduction

The manufacturing of organic electronic devices using solution-based deposition techniques, such as coating and printing, have drawn extensive attention because they can be upgraded to industrial scale [1,2,3,4,5]. From the commercial point of view these techniques have distinguishable advantages, such as the low-cost of processing and high throughput, as well as being more suitable for fabrication of flexible electronic devices in comparison to vacuum deposition techniques [6,7,8,9]. Many multilayer devices, including organic light emitting diodes (OLEDs) [10], photovoltaics [11], transistors [12], and sensors [13] have been fabricated by partially using this technique for the deposition of some layers. The main challenge for improving the performance of solution-processed devices is the ink formulation that will ensure homogeneous film formation and allow multi-layer deposition [16,17,18]

Methods

Results

Conclusion