High voltage CMOS backplane for OLED microdisplays

Researchers at Fraunhofer in Germany have made a significant breakthrough in the field of OLED microdisplays by developing a high voltage CMOS backplane that enhances the brightness of these displays. OLEDs have traditionally faced limitations in achieving very high brightness levels in harsh environments, leading to the exploration of microLEDs as an alternative. However, microLEDs encounter efficiency challenges at extremely high pixel densities required for high-resolution microdisplays, necessitating operation with more than 1A/cm², particularly for full-color displays.

The current density for OLEDs in long-lifespan operation typically remains below 100 mA/cm². To address this limitation, researchers have previously demonstrated the potential for significant improvement by stacking OLED layers on top of each other. This stacking technique enhances brightness but also introduces challenges such as increased voltage drop and swing across the OLED stack.

In response to these challenges, the team at Fraunhofer IPMS has developed a cutting-edge high-voltage CMOS backplane specifically designed for high-brightness OLED microdisplays. Dr. Uwe Vogel, the head of Microdisplays and Sensors at Fraunhofer IPMS, highlighted the innovative pixel cell design that enables a voltage swing of over 10 volts, facilitating the operation of multiple stacked, top-emitting OLED layers.

According to Dr. Vogel, this technological advancement allows for achieving multiples of the maximum emission with high current efficiency while maintaining a constant current density, ultimately enabling full-color maximum brightness exceeding 10,000 cd/m² while ensuring lifespan and reliability. Fraunhofer IPMS, known for its expertise in developing backplanes for various technologies, particularly microdisplays, has focused on CMOS technology for mainstream manufacturing, showcasing a comprehensive understanding of the entire process chain from feasibility studies to pilot production in OLED microdisplays.

The introduction of the high voltage CMOS backplane opens up new possibilities for stacked OLED microdisplays in augmented reality and virtual reality applications, offering a brightness level of 10,000 cd/m². This advancement significantly expands market opportunities and paves the way for enhanced visual experiences in various industries.