Community Research and Development Information Service - CORDIS


SOLEDLIGHT Report Summary

Project ID: 643791
Funded under: H2020-EU.

Periodic Reporting for period 1 - SOLEDLIGHT (Solution Processed OLEDs for Lighting)

Reporting period: 2015-01-01 to 2016-06-30

Summary of the context and overall objectives of the project

Highly efficient organic electroluminescent devices (OLEDs) are a technology that promises to reduce significantly the electricity consumption. The estimated market for OLED lighting products is large ($8 billion) and European lighting manufacturers are ideally positioned to capture a large part of it.
Glass OLED products prepared by vacuum evaporation techniques have been demonstrated with good performances, yet the main bottle neck for larger market introduction is the high cost. At high production volumes the cost of OLED production is directly related to the efficiency of materials usage which is estimated to be 70 % for vacuum deposition and 90 % via solution processing.
Hence, roll-to-roll solution processed OLEDs, will lead to a significant price reduction due to more efficient organic material usage, lower capital investments and higher throughput. Additionally, these OLEDs will be produced directly on flexible substrates allowing for new light weight and space saving designs.
Society will benefit as with the availability of these flexible efficient lighting sources electricity consumption will be reduced.

SOLEDLIGHT will develop OLEDs in two ways. The first uses an intermediate approach implying both solvent and vacuum based processing steps, to so called “hybrid” approach. The second type of OLEDs will be produced using only solvent based processing steps (coating methods). In this way SOLEDLIGHT will develop fully S2S and R2R solution processed multilayer OLEDs with power efficiencies > 100 lm/W and lifetimes > 15000 hours at 3,000 cd/m2.

SOLEDLIGHT has assembled a consortium comprising a Osram (leading OLED manufacturer and integrator), Solvay (leading OLED materials manufacturer), TNO/Holst Centre (an excellence centre for organic devices with a state-of-the-art R2R line and leading universities in the field (Univ. Valencia, EPFL and Imperial College).

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Using materials provided by Solvay a starting point hybrid OLED architecture has been identified and implemented at both Holst Center and University of Valencia. The materials required for the preparation of the OLEDs have successfully been upscaled by Solvay reducing significantly the side products and waste. It is not trivial to obtain similar performances in complex devices with nanometer scale layers at different laboratories using different processing tools, yet due to the combined efforts very similar performances are obtained using a standardized OLED at Holst and University of Valencia. This is an important achievement and prerequisite for the rapid implementation of further material and device improvements. The performance of this initial stack was promising yet the reproducibility was not. This was due to the use of one difficult to handle material. Using the expertise of Osram, Holst and Univ. of Valencia an alternative material has been identified that is much easier to handle and leads to reproducible results. EPFL has developed alternative phosphorescent molecules that are the core of the OLED with the aim to increase the efficiency. Several promising materials have emerged, and some of them lead to high efficiency devices. Implementation in the Hybrid OLED stack has not yet lead to an increase in the performance.
SOLEDLIGHT also aims to prepare OLED using only solution based processes (coating) on flexible substrates. This implies that the processing steps need to be below the softening temperature of the plastic substrates used. Additionally, as high efficiency OLEDs consist of at least 4 separate layers, each of several tens of nanometer thickness, it is important to prevent the removal of previously deposited layers due to the solvents. To achieve this, Imperial College has prepared molecules that can insolubilize the active materials in the different OLED layers. When the active molecules are polymers this approach works, yet we have found that for smaller active molecules it is more difficult to insolubilize them. Fortunately, we have found interesting materials set with solubility parameters allowing for the use of orthogonal solvents. This means that the solvent used for one layer does not dissolve the layer underneath. Using these orthogonal solvent combinations fully solution processed OLEDs with power efficiencies up to 15 lm/W have been prepared, which is a very promising result.
Further improvements in efficiency are expected from promising development at EPFL and Imperial regarding phosphorescent molecules and electron transporting molecules.
SOLEDLIGHT does not only aim to prepare OLEDs, but also to integrate them into Luminaires. Out of a few design options, the Flamingo luminaire emerged that uses 5 large area OLED panels (at this stage in the project still rigid) that are special in that they have only one contact side, allowing for additional design freedom. See a picture of the luminaire and some of the project collaborators below.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

SOLEDLIGHT has identified an alternative material that leads to efficient electron injection into the hybrid OLEDs. This improves the reproducibility and hence will allow a much better yield in production.
Several solvent-material combinations were identified that allow the sequential coating of active layers at temperatures compatible with plastic substrates.
SOLEDLIGHT has designed a single side contactable OLED showing uniform light emission over the complete area that are easily integrated in a demonstrator Luminaire.

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