Spectrally selective optical, hot-electron, and photothermal effects in planar Tamm plasmon nanostructures

Abstract Multifunctional photonic nanostructures integrating optical filtering, hot-electron photodetection, and photothermal conversion are highly desirable for advanced optoelectronic and energy harvesting systems. Nevertheless, it remains challenging to achieve synchronous spectral-selective optical, electrical, and thermal responses in a single nanostructure. This work demonstrates that planar Tamm plasmon nanostructures can achieve simultaneous optical, electrical, and thermal spectral selectivity. A multilayer design, consisting of a Ge/MgF2 distributed Bragg reflector on a silver film, achieves near-perfect absorption (~99%) at 1660 nm with a narrow full width at half maximum (~32 nm). This resonance induces intense electromagnetic confinement at the Ag/Ge interface, resulting in a wavelength-selective hot-electron photoresponsivity of 35 mA/W and a peak local temperature of 75.4°C under resonant illumination. Optical and thermal responses all exhibit matched spectral selectivity, confirming the structure's multifunctional capabilities. The device is fully planar and compatible with lithography-free fabrication, offering practical advantages for integrated optoelectronic and energy-conversion systems. The study establishes a new route to integrate wavelength-selective filtering, hot-electron photodetection, and photothermal conversion within a single planar nanostructure as a high-performance platform.