Suppressing molecular aggregation in solution processed small molecule organic light emitting diodes

• Suppressing molecular aggregation in small-molecule OLEDs.
• Solution processing of small-molecule layers.
• Influence of electrical isolating polymers on the OLED performance.
• STEM-HAADF investigations of small-molecule layers.

Solution processing of low-molecular weight organic materials for optoelectronic devices is a challenging task due to often strong molecular aggregation. We present a facile and universal route for suppressing the aggregation of molecules during wet-deposition of emission layers for organic light emitting diodes by incorporating electronically inactive polymers. Moderate polymer concentrations of about 10 wt.% lead to only minor changes of the electrical performance while at the same time improving the film formation and consequently the device luminance significantly. The device performance matches the performance of vacuum processed devices with the same device architecture.

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