Hybrid 2D/0D SnSe2-SnO2 vertical junction based high performance broadband photodetector

Highlights: • One step, facile synthesis of 2D-SnSe₂ nanoflakes and 0D quantum dots. • Vertical heterojunction based Schottky photodetector resulting in an ultralow limit of detection of 9 μW/cm². • Broadband detector displayed high responsivity, EQE and detectivity values. -- Abstract: Despite their high absorption coefficients, most two-Dimensional (2D) Transition Metal Dichalcogenides (TMDC) based photodetectors have a narrow range of light absorption and employ sophisticated fabrication methods. To overcome this, we propose a ²D–⁰D hybrid heterojunction-based broadband photodetector with Tin Diselenide (SnSe₂)/Tin Oxide (SnO₂) hybrid structure to enhance the range of detection and performance of the photodetector. The ²D and ⁰D nanoparticles were synthesized using a simple, cost-effective, one-step hydrothermal method. Detailed physicochemical characterization studies demonstrate the formation of 2D hexagonal layers of SnSe₂ nanoflakes with absorption in visible and near IR regions and rutile tetragonal structure of SnO₂ Quantum dots (QDs) with absorption in UV region. The fabricated photodetector shows superior responsivity of 47.9, 16.8, and 6.51 mA/W in UV, VIS, and NIR light with enhanced light-matter interaction. The SnSe₂/SnO₂ heterostructures demonstrated an efficient interlayer charge transfer due to the strong coupling. The superior performance of the photodetector can be attributed to the sizeable tuning of bandgap upon optical excitation in the bulk heterojunction wherein the photocarriers are injected into the SnSe₂ nanoflakes for efficient light absorption in the broadband spectrum. The response time of this device was observed to be 0.5, 0.5, and 0.93 s under the illumination of UV, visible, and NIR lights, respectively. The flexibility studies display excellent robustness and mechanical stability for ~2000 bending cycles at ambient conditions. Hence, due to its flexibility, low power, and low cost, the strategy outlined here is ideal for applications like wearable electronics, flexible security, and surveillance systems.