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1. Mid‐Infrared LEDs Based on Lattice‐Mismatched Hybrid IV–VI/III–V Heterojunctions

   https://doi.org/10.1002/adom.202503448  

   Meyer, Jarod E; Rodriguez, Biridiana; Nordin, Leland; Mukherjee, Kunal (March 2026, Advanced Optical Materials)

   ABSTRACT Light‐emitting diodes (LEDs) can bridge the gap between narrow linewidth, expensive lasers and broadband, inefficient thermal globars for low‐cost chemical sensing in the mid‐infrared (mid‐IR). However, the efficiency of III–V‐based mid‐IR LEDs at room temperature is low, primarily limited by strong nonradiative Auger‐Meitner recombination that is only partially overcome with complex quantum‐engineered active regions. Here, we exploit the intrinsically low Auger‐Meitner recombination rates of the IV–VI semiconductors PbSe and PbSnSe, while leveraging the mature III–V platform through the fabrication of hybrid heterojunctions that mediate the ∼8% lattice mismatch to GaAs. Electrically injected n‐PbSe/p‐GaAs LEDs emit at 3.8 µm with output powers up to 400 µW under pulsed operation and a peak wall plug efficiency of 0.08% at room temperature, approaching the performance of commercial III–V LEDs at similar wavelengths. Incorporating 7% Sn extends the emission to 5 µm in GeSe/PbSnSe/GaAs LEDs with output powers up to 45 µW. Notably, both devices operate despite threading dislocation densities on the order of 10⁹cm⁻², underscoring the potential of hybrid IV–VI/III–V heterojunction architectures. We show that combining the complementary advantages of IV–VI and III–V semiconductors offers a simple and efficient mid‐IR optoelectronic platform for a rapidly expanding set of applications. 

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2. Broadband infrared photodetection using a narrow bandgap conjugated polymer

   https://doi.org/10.1126/sciadv.abg2418  

   Vella, Jarrett H.; Huang, Lifeng; Eedugurala, Naresh; Mayer, Kevin S.; Ng, Tse Nga; Azoulay, Jason D. (June 2021, Science Advances)

   Photodetection spanning the short-, mid-, and long-wave infrared (SWIR-LWIR) underpins modern science and technology. Devices using state-of-the-art narrow bandgap semiconductors require complex manufacturing, high costs, and cooling requirements that remain prohibitive for many applications. We report high-performance infrared photodetection from a donor-acceptor conjugated polymer with broadband SWIR-LWIR operation. Electronic correlations within the π-conjugated backbone promote a high-spin ground state, narrow bandgap, long-wavelength absorption, and intrinsic electrical conductivity. These previously unobserved attributes enabled the fabrication of a thin-film photoconductive detector from solution, which demonstrates specific detectivities greater than 2.10 × 10 9 Jones. These room temperature detectivities closely approach those of cooled epitaxial devices. This work provides a fundamentally new platform for broadly applicable, low-cost, ambient temperature infrared optoelectronics. 

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3. Heterojunction Engineering of All-Inorganic CsPbI3 Perovskite for High-Responsivity SWIR Photodetectors Performed at Room Temperature

   https://doi.org/10.53941/mi.2025.100023  

   Schmidt, Sydney; Fisher, Haley; Li, Xia; Brown, Jesse B; Qian, Yuqin; Malmquist, Van; Harutyunyan, Avetik; Chen, Gugang; Rao, Yi (July 2025, Materials and Interfaces)

   Short-wave infrared (SWIR) light, 0.9–2.5 μm wavelengths, has widespread applications, including inspection processes, nighttime imaging, and machine vision. As such, there is increasing demand for practical and effective SWIR detectors. Many current SWIR photodetectors are based on high-cost materials and require cryogenic cooling. Perovskite materials, including CsPbI3, have been effectively used as photodetectors in the UV to near IR ranges, but their large bandgaps limit their use for lower energy SWIR light. In this report we introduce an all-inorganic perovskite photodetector based on CsPbI3 with heterojunction engineering for efficient and practical detection in the SWIR range at room temperature. The devices undergo a simple, solution-based fabrication process which includes spin-coating under ambient conditions and moderate annealing temperatures. Without additional cooling, the SWIR devices produce excellent results at room temperature with responsivity of 1.65 × 103 A W−1 and a specific detectivity of 8.0 × 1010 Jones under 0.28 mW cm−2 of 1310 nm light and bias of −5 V. This material shows not only high response but also high sensitivity, making it stand out in the field of SWIR photodetection with the additional benefits of low-cost production and room temperature operation. 

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4. Wavelength-scalable mid-infrared photodetectors based on photon-assisted tunneling in MIM metasurfaces

   https://doi.org/10.1364/JOSAB.571626  

   Heidarzadeh, Parham; Chen, Jimmy Ching-Ming; Zhou, Zhixian; Chen, Pai-Yen (January 2025, Journal of the Optical Society of America B)

   We propose zero-bias, wavelength-scalable, and polarization-selective mid-infrared photodetectors based on metal–insulator–metal (MIM) metasurfaces. Specifically, these photodetectors leverage the second-order quantum conductivity sourced from photon-assisted tunneling and strong electric field localization in the MIM nanojunction to achieve efficient optical rectification. We show that by tailoring metasurface geometry, the incident infrared radiation can be efficiently coupled into the MIM heterojunction, with certain wavelength and polarization selectivity, and the optical rectification effect can be achieved with a photoresponsivity as high as tens of mA/W. Such results may pave a promising route toward the next-generation mid-infrared photodetection and energy harvesting. 

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5. Mid-Infrared Spectrometer Based on Tunable Photoresponses in Pdse ₂

   https://doi.org/10.1142/S0129156424400639  

   Lee, Jea Jung; Levi, Adi; Naveh, Doron; Xia, Fengnian (September 2024, International Journal of High Speed Electronics and Systems)

   Mid-infrared (mid-IR) photodetection is important for various applications, including biomedical diagnostics, security, chemical identification, and free-spacing optical communications. However, conventional “photon” mid-IR photodetectors require liquid nitrogen cooling (i.e., MCT). Furthermore, acquiring mid-IR spectra usually involves a complex and expensive Fourier Transform Infrared spectrometer, a tabletop instrument consisting of a meter-long interferometer and MCT detectors, which is not suitable for mobile and compact device applications. In this work, we present tunable photoresponsivity in the mid-IR wavelength in palladium diselenide (PdSe₂) – molybdenum disulfide (MoS₂) heterostructure field-effect transistors (FETs), operating at room temperature. Furthermore, we applied a tunable membrane cavity to modulate the Fabry–Pérot resonance to modulate the absorption spectrum of the device layer. We used a robust polyetherimide (PEI) membrane with CVD-grown graphene to electrically tune the membrane structure. For the next step, we will integrate the PdSe₂-based photodetector and tunable membrane to increase detection sensitivity and spectrum tunability to realize the ‘learning’-based spectroscopy. 

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