A Multi-Interface Engineered Bi ₂ Se ₃ /PtSe ₂ Heterojunction on Pyramid Si Nanostructures for Self-Powered Near-Infrared Photodetection

The development of high-performance near-infrared (NIR) photodetectors (PDs) in self-powered operation is crucial and essential for next-generation optoelectronic applications. Herein, we report a Bi 2 Se 3 /PtSe 2 -based heterojunction on pyramid-Si (Pr-Si) PD that integrates topological and transition metal dichalcogenide materials with light-trapping of Pr-Si nanostructures to achieve a self-powered and highly enhanced NIR photoresponse. The Pr-Si substrate offers an enlarged surface area and efficient photon confinement, while the conformally coated semi-metallic PtSe 2 nanosheets form a conductive interfacial layer that promotes charge transfer. The optimized Bi 2 Se 3 /PtSe 2 /Pr-Si-based PD device exhibits an ∼9-fold enhancement in responsivity (∼202 A/W) compared to the PtSe 2 /Pr-Si-based (∼21.4 A/W) PD device at 5 V in the NIR region, demonstrating efficient charge transport and suppressed recombination. Additionally, the Bi 2 Se 3 /PtSe 2 /Pr-Si-based PD device exhibits self-powered photodetection with an ∼10-fold increase in responsivity (∼853 mA/W) as compared to the PtSe 2 /Pr-Si-based (∼80.8 mA/W) PD device. The fabricated Bi 2 Se 3 /PtSe 2 /Pr-Si PD device exhibits stable, repeatable ON–OFF switching behavior under NIR illumination. These findings highlight the synergistic effect of the Bi 2 Se 3 and PtSe 2 heterojunction, underscoring the potential of hybrid nanostructures for high-performance, energy-efficient, and self-powered NIR photodetection.