Researchers Demonstrate 15% Increase in Efficacy and Lifetime by Using Ultrastable Glass
May 28, 2018
Researchers from the Universitat Autònoma de Barcelona and Technische Universität Dresden have demonstrated using ultrastable film formation to improve the performance of OLEDs. In their joint paper published in Science Advances with the title 'High-performance organic light-emitting diodes comprising ultrastable glass layers', the researchers show in a detailed study that significant increases of efficiency and operational stability (> 15% for both parameters and all cases, significantly higher for individual samples) are achieved for four different phosphorescent emitters. To achieve these results, the emission layers of the respective OLEDs were grown as ultrastable glasses - a growth condition that allows for thermodynamically most stable amorphous solids. Illustration summarizing the nanoscale difference of ultrastable glasses compared to conventional ones and the impact on the layer and device properties of OLEDs. The discovery is an optimization, which involves neither a change of materials used nor changes to the device architecture. This concept can be universally explored in every given specific OLED stack, which will be equally appreciated by leading industry and includes thermally activated delayed fluorescence (TADF) OLEDs. Furthermore, the improvements that, as shown by the researchers, can be tracked back to differences in the exciton dynamics on the nanoscale suggest that other fundamental properties of organic semiconductors (e.g. transport, charge separation, energy transfer) can also be equally affected. The research leading to these results was partly carried out in the project 'Modeling stability of organic phosphorescent light-emitting diodes (MOSTOPHOS)' funded by the European Union's Horizon 2020 research and innovation program (grant agreement no. 646259). Currently, this concept is being explored together with Cynora GmbH, a MOSTOPHOS partner and a world-leading company in development of TADF emitters.