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 crucial for achieving high-performance 2D photodetectors. Here, a MoSSe/GeP heterostructure is fabricated using an Elvacite pickup transfer strategy, enabling a clean van der Waals junction and contamination-free electrical contacts. Structural and spectroscopic characterizations, including AFM, Raman spectroscopy, and Raman mapping, collectively confirm high crystalline quality, uniform layer thickness, and a chemically sharp interface. Electrical transport measurements further show that GeP exhibits p-type behavior, whereas Janus MoSSe displays n-type conduction, thereby confirming their suitability as complementary semiconductors for p-n junction formation. The pristine p-n junction device exhibits strong rectification (2.2 × 10³ 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 × 10⁴ AW^-1, 3.55 × 10¹³ Jones, and 2.36 × 10⁴% to 4.05 × 10⁴ AW^-1, 7.6 × 10¹³ Jones, and 1.41 × 10⁵%, respectively, at 455 nm, 5.53 mWcm^-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 × 10²%, responsivity of 8.75 AW^-1, and detectivity of 0.56 × 10¹⁰ Jones, confirming self-powered functionality. These enhancements originate from spectral resonance, efficient QD-to-MoSSe charge transfer, reduced recombination, and photogating-assisted gain.