Skoltech team builds room-temperature infrared detector with carbon nanotubes and lithium niobate

Researchers at Skolkovo Institute of Science and Technology say they have built a broadband infrared phototransistor that works at room temperature and reaches detectivity near the limit for uncooled thermal sensors. The device uses a pyroelectric lithium niobate crystal to gate a sparse single-walled carbon nanotube network, pointing to cheaper, lighter infrared sensing for imaging, gas detection and communications.

Why it matters: - The detector works without cryogenic cooling, which could reduce the size, cost and power demand of infrared sensing systems. - The device responds across the visible range to 9.3 µm, which makes it relevant for thermal imaging, gas sensing and short-range optical communications. - The reported performance approaches the theoretical limit for uncooled thermal detection.

What happened: - A Skolkovo Institute of Science and Technology team led by Dr. Svetlana I. Serebrennikova and Professor Albert G. Nasibulin demonstrated a room-temperature infrared phototransistor based on single-walled carbon nanotubes and lithium niobate. - The paper was made available online on May 6, 2026 and published in Opto-Electronic Advances, Volume 9, Issue 5, on May 14, 2026. - The original paper is titled “Highly sensitive SWCNT-based pyroelectric phototransistors for broadband room temperature infrared detection.” - The DOI is the published paper.

The details: - The device uses the pyroelectric effect in lithium niobate: infrared light warms the crystal slightly, which changes its polarization and creates an electric field. - That field acts like a gate voltage for the carbon nanotube network and changes its conductivity by up to 10^5. - The active channel is a sparse, sub-percolating network of semiconducting single-walled carbon nanotubes. - The team grew the nanotube networks with a refined aerosol chemical vapor deposition method. - The films were transferred onto a z-cut lithium niobate surface with a capillary transfer technique. - The dry transfer method avoids surfactants and contaminants that can hurt nanotube electronics in standard deposition processes. - Metal contacts were patterned by lithography. - The finished detectors operate from visible wavelengths to 9.3 µm at room temperature. - The devices reached specific detectivities on the order of 10^10 cm·Hz1/2/W. - The performance outpaced graphene-based pyroelectric devices by several orders of magnitude. - The work builds on the fact that graphene lacks a bandgap, while semiconducting carbon nanotubes can change conductivity much more strongly under gating.

Between the lines: - The study targets a long-standing tradeoff in infrared sensing: high sensitivity usually requires cooling, but cooling adds bulk and cost. - The choice of semiconducting carbon nanotubes is central. Their bandgap gives the gate-modulated response that graphene cannot provide as effectively. - The design also shows how a thermal signal can be amplified into a much larger electrical readout without changing the basic room-temperature operating model. - The reported 2-second response time is limited by heat diffusion through the 500 µm-thick lithium niobate substrate, so the substrate becomes the main bottleneck rather than the nanotube channel. - This suggests the device is promising for sensitivity first, with speed improvements still needed for faster imaging tasks.

What’s next: - The team says thinner substrates or membrane structures should speed up the thermal response. - Future work also aims to reduce hysteresis with protective coatings. - The researchers want to improve reproducibility in the semiconducting-channel networks. - Better thermal coupling to heat sinks could sharpen both response speed and spatial resolution in beam imaging. - If those changes hold up, the platform could move toward portable thermal cameras, handheld gas sensors and drone-mounted detectors.

The bottom line: - Skoltech researchers have shown that a pyroelectric lithium niobate crystal and sparse carbon nanotubes can deliver broadband infrared detection at room temperature with unusually high sensitivity.