Efficient and Self-Powered MoSSe/GeP p-n Diode Enabled by Perovskite Lead-Free Quantum Dots

A residue-free interface and strong light-matter coupling are critical for high-performance 2D photodetectors. Here, a MoSSe/GeP heterostructure is fabricated using Elvacite pickup transfer, enabling a clean van der Waals junction and contamination-free electrical contacts. Structural (AFM) and spectroscopic (Raman and Raman mapping) analyses collectively demonstrate high crystalline quality, uniform layer thickness, and a chemically sharp interface, firmly establishing GeP and Janus MoSSe as complementary p- and n-type semiconductors. The pristine p-n junction device exhibits strong rectification (2.2 × 10 ³ at V _g  = − 40 V). After sensitization with lead-free perovskite quantum dots ( λ _em  ≈ 510 nm), the QD-MoSSe/GeP heterostructure exhibits a pronounced built-in field-driven photocurrent of approximately 0.25 µA at zero bias, confirming efficient interfacial separation. QD integration enhances responsivity, detectivity, and EQE from 1.64 × 10 ⁴ A W ^-1 , 3.55 × 10 ¹³ Jones, and 2.36 × 10 ⁴ % to 4.05 × 10 ⁴ A W ^-1 , 7.6 × 10 ¹³ Jones, and 1.41 × 10 ⁵ %, respectively, at 455 nm, 5.53 mW cm ^-2 , and V _ds = 1.5 V. Photoexcitation in the quantum-dot layer enables charge transfer into the MoSSe channel, while long-lived trapped charges induce electrostatic gating, leading to pronounced photogating-assisted gain. In addition, under zero-bias operation, the QD-sensitized device achieves an EQE of 8.4 × 10 ² %, responsivity of 8.75 A W ^-1 , and detectivity of 0.56 × 10 ¹⁰ Jones, confirming self-powered functionality. These enhancements arise from spectral resonance with QD emission, efficient QD-to-MoSSe charge transfer, and reduced recombination. This study demonstrates that clean pickup assembly combined with QD sensitization provides a scalable pathway toward high-sensitivity, broadband (365–940 nm), and stable 2D optoelectronic devices.