Research Paper: Single-pixel spectrometer based on a bias-tunable tandem organic photodetector

Summary

This study introduces a novel single-pixel spectrometer based on a bias-tunable tandem organic photodetector (OPD), designed to provide compact and lightweight spectral sensing without the need for external filters or moving parts. The researchers leveraged complementary organic semiconductors (D18-Cl, L8BO, PTB7-Th, and COTIC-4F) in a tandem cell design where sub-cells have opposing polarity, enabling a bias-tunable spectral response from ultraviolet to near-infrared (400–1,000 nm). Key findings include the accurate reconstruction of both narrow and broad light spectra, demonstrating a peak wavelength accuracy within 0.18 nm and a spectral resolution of 1 nm. The device achieves a responsivity of 0.27 A W⁻¹, a detectivity of 1.4 × 10¹² Jones, and fast rise/fall times of 2.82/3.72 μs, operating with a low external bias sweep of less than 1 V.

Why it matters

These findings are crucial for advancing miniaturized spectrometry by overcoming the limitations of traditional, bulky instruments that rely on filters or moving parts, which often suffer from trade-offs in spectral resolution and bandwidth. This compact, two-terminal, low-power design offers a scalable solution for high-performance imaging spectrometers, enabling new possibilities for portable diagnostics, wearable sensors, real-time in-field analysis, and seamless integration into consumer devices and lab-on-a-chip systems.

How Fluxim tools used

The Fluxim Paios platform was used to measure transient photocurrent. This was instrumental in characterizing the detector's speed, specifically determining the rise and fall times. The precise measurement of these dynamic properties ensured that the detector could quickly sweep through the modulating voltages required for efficient spectral reconstruction.

Publication Details

Schrickx, H.M., Al Shafe, A., Moore, C., Pei, Y., So, F., Kudenov, M., O’Connor, B.T. (2025), Single-pixel spectrometer based on a bias-tunable tandem organic photodetector. Device 3, 100866. https://doi.org/10.1016/j.device.2025.100866