The Seebeck effect refers to the production of an electric voltage when different temperatures are applied on a conductor, and the corresponding voltage-production efficiency is represented by the Seebeck coefficient. We report a Seebeck effect: thermal generation of driving voltage from the heat flowing in a thin PtSe2/PtSe2 van der Waals homostructure at the interface. We refer to the effect as the interface-induced Seebeck effect. By exploiting this effect by directly attaching multilayered PtSe2 over high-resistance PtSe2 thin films as a hybridized single structure, we obtained the highly challenging in-plane Seebeck coefficient of the PtSe2 films that exhibit extremely high resistances. This direct attachment further enhanced the in-plane thermal Seebeck coefficients of the PtSe2/PtSe2 van der Waals homostructure on sapphire substrates. Consequently, we successfully enhanced the in-plane Seebeck coefficients for the PtSe2 (10 nm)/PtSe2 (2 nm) homostructure approximately 42% compared to that of a pure PtSe2 (10 nm) layer at 300 K. These findings represent a significant achievement in understanding the interface-induced Seebeck effect and provide an effective strategy for promising large-area thermoelectric energy harvesting devices using two-dimensional transition metal dichalcogenide materials, which are ideal thermoelectric platforms with high figures of merit.

Novel, low‐voltage, high‐detectivity, solution‐processed, flexible near‐infrared (NIR) photodetectors for optoelectronic applications are realized and their optoelectronic properties are investigated for the first time. This is achieved by synthesizing Ag2Se nanoparticles (NPs) in aqueous solutions, and depositing highly crystalline Ag2Se thin films at 150 °C with redistributed Ag2Se NPs in aqueous inks. The high conductivity and low trap concentration of the 150 °C annealed Ag2Se films result from the Ag formed inside the films and the improved film quality, respectively. These factors are both critical for the realization of high‐performance flexible photodetectors. The fabricated device exhibits a high detectivity of 7.14 × 109 Jones (above 1 × 109) at room temperature, delivering low power consumption. This detectivity is superior to those of reported low band‐gap semiconductor systems, although the device has undergone 0.38% compressive and tensile strains. Moreover, the performance of the device is better than that of MoS2‐based phototransistors, black arsenic phosphorus field‐effect transistors, or commercial thermistor bolometers at room temperature (D* ≈ 108 Jones), and is exposed to mid‐infrared light.

The spin current is significantly limited by the spin‐orbit interaction strength, material quality, and spin‐mixing conductance at material interfaces. Such limitations lead to spin current decay at the interfaces, which severely hinders potential applications in spin‐current‐generating thermoelectric devices. Thus, methodical studies on the enhancement of spin currents are indispensable. Herein, a novel approach for enhancing the spin current injected into a normal metal, Pt, using interface effects with a ferromagnetic insulator, yttrium iron garnet (YIG), is demonstrated. This is accomplished by inserting atomically thin monolayer (ML), tungsten diselenide (WSe2) between Pt and YIG layers. A comparative study of longitudinal spin Seebeck effect (LSSE) measurements is conducted. Two types of ML WSe2 (continuous and large‐area ML WSe2 and isolated ML WSe2 flakes) are used as intermediate layers on YIG film. Notably, the insertion of ML WSe2 between the Pt and YIG layers significantly enhances the thermopower, VLSSE/ΔT by a factor of approximately 5.6 compared with that of the Pt/YIG reference sample. This enhancement in the measured LSSE voltages in the Pt/ML WSe2/YIG trilayer can be explained by the increased spin‐to‐charge conversion at the interface owing to the large spin‐orbit coupling and improved spin mixing conductance with the ML WSe2 intermediate layer.

Two-dimensional (2D) PtSe 2 is rapidly emerging as a promising candidate for developing devices that exhibit a significantly enhanced thermoelectric power factor because of its thickness-modulation-induced tunable semiconductor-to-semimetal transition characteristic. This interesting phenomenon motivated us to measure the in-plane Seebeck coefficients and electrical conductivities of large-area 2D PtSe 2 thin films with approximately 2−15 nm thicknesses. We observed an outstanding in-plane Seebeck coefficient of ∼73.7 μV/K and a high electrical conductivity of ∼216 S/cm in the 9-nm-thick 2D PtSe 2 film than in the ∼6-nm-thick 2D PtSe 2 film at 300 K. Our observations suggest that thickness-dependent semiconductor-to-semimetal transitions in PtSe 2 -based materials offer a distinguishable advantage for enhancing the power factor of 2D PtSe 2 -based thermoelectric devices.

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