Enhanced Photoresponsivity of Perovskite QDs/Graphene Hybrid Gate‐Free Photodetector by Morphologically Controlled Plasmonic Au Nanocrystals

Abstract Owing to their excellent carrier mobility, high absorption coefficient, exceptional quantum efficiency, and low‐cost solution processability, perovskite quantum dots (PQDs) are a promising candidate for photodetection. However, PQDs‐based photodetectors typically show poor optoelectronic performances, mainly limited by their weak light–matter interaction. In this work, MAPbBr₃ PQDs are hybridized with graphene (Gr) and morphologically controlled plasmonic gold nanocrystals (AuNCs) to demonstrate a superior photodetector at 432 nm through a synergetic effect. The experimental results indicate that three shaped AuNCs (i.e., sphere, the octahedron (OD), and rhombic dodecahedron (RD)) all contribute to better photodetection behaviors due to surface trap state passivation and enhanced charge carrier densities with longer lifetime compared to that of pristine PQDs. In particular, the PQDs/RD‐AuNCs/Gr system demonstrates a record‐high responsivity of 2.7 × 10⁵ A W⁻¹, a detectivity of 4.9 × 10¹³ Jones, and external quantum efficiency (EQE) of 7.9 × 10⁷% at 1.6 µW cm⁻² illumination power density of 432 nm wavelength with a lowest applied voltage of 1.0 V for a gate‐free PQDs/AuNCs/Gr‐based photodetector. Furthermore, to the authors’ knowledge, this device shows the highest responsivity among the PQDs/AuNCs/Gr‐based electrostatic gate‐free lateral configuration photodetectors.