Display-integrated optical sensing for multifunctional, next-generation displays
CEA-Leti Demonstrates Combined MicroLED and Organic Photodetector Architecture.
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Illustration of co-packaged OPD and MicroLED matrix
Photos credit: Eric Kroemer/CEA-Leti
CEA-Leti has demonstrated a co-packaged microLED and organic photodetector (OPD) architecture that enables optical sensing functions to be integrated directly into a microLED display—without compromising display performance. The work was presented at SPIE Photonics West and details a system-level approach combining device design, electronics, and modeling for multifunctional display applications.
From pixels to sensing platforms
MicroLEDs deliver high radiance while occupying only a fraction of the pixel area, leaving room for additional functions. Leveraging this advantage, CEA-Leti developed a microLED matrix co-packaged with a tailored OPD, both optimized for green wavelengths relevant to photoplethysmography (PPG) signal extraction. This enables sensing capabilities to be embedded directly into the display’s front plane rather than relegated to bezels or external sensors.
System-level performance validation
To move beyond component-level proofs, the team built a dedicated electronic platform to characterize the full signal chain—from microLED driving through the device under test to photodetection and readout. Lock-in detection techniques were used to enhance signal-to-noise ratio and suppress static parasitics, a critical requirement for biosensing where AC/DC ratios matter.
Validation employed optical phantoms replicating the absorption and scattering properties of biological tissue, enabling controlled, repeatable testing. Experimental data were combined with analytical modeling to derive a closed-form relationship linking microLED operating conditions, OPD responsivity, device reflectance, and detected signal.
Key results
- Optical output: up to 12 mW at 525 nm from the microLEDs
- OPD responsivity: tuned via ZnPc active-layer thickness to 0.083 A/W at the target wavelength
- Architecture advantage: sensing and display functions coexist at pixel level without trade-offs in brightness or resolution
Characterization platform including custom electronic board and biological phantom mimicking human tissues
Photos credit: Eric Kroemer/CEA-Leti
Why microLED matters
Unlike OLED-based approaches—where display and sensing compete for surface area—the microLED/OPD architecture supports integrated sensing without sacrificing visual performance. The end-to-end, fully characterized system establishes a scalable foundation for displays that combine visual output with adaptive sensing functions.
A co-design methodology
“This work illustrates CEA-Leti’s system-technology co-design approach, from concept definition and microLED technology to photodetector co-design, electronics development, and experimental validation under realistic conditions,” said Michaël Pelissier, lead author of the paper. “By combining hardware development with analytical modeling and simulation, we establish a concrete framework for evaluating and scaling sensing-integrated display architectures.”
Looking ahead
The architecture is inherently scalable across pixel pitches and resolutions, from smartphones and wearables to monitors and televisions. The results provide practical know-how for designing multifunctional displays where sensing and visualization are conceived together at the system level.
This work is part of the IPCEI Microelectronics and Connectivity program and is supported by French public authorities under France 2030.
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