Heterostructures made from bone-like plasmonic Au nanoantennas and ZnO quantum dots for broadband photodetectors

Abstract

Excitation of plasmon can generate strong light absorption and scattering, a giant electromagnetic (EM) field, and hot electrons, thereby offering an effective way to improve the performance of photodetectors. However, the incorporation of plasmonic nanostructures in photodetectors is largely limited by their high fabrication cost, which usually involves tedious time-consuming physical vapor deposition and complex subsequent treatment processes. Herein, we report a low-cost solution-processable method to prepare bone-like Au nanoantennas (BLAuNAs) to construct BLAuNAs/ZnO heterostructures for broadband photodetectors, accomplished via interfacial self-assembly of Au NPs, electrochemical treatment, and finally spin coating of BLAuNAs with a ZnO quantum dot (QD) film. The resultant BLAuNAs/ZnO heterostructures not only improve the intrinsic ultraviolet (UV) response of the ZnO QD film but also extend the photoresponse to the visible region because of interband transition-derived high-energy electrons, plasmon-derived hot electrons, and EM field enhancement effects. Therefore, under 365 and 532 nm light illumination, the responsivity of the photodetector made from the optimized BLAuNA2/ZnO heterostructures is 61.4 mA W⁻¹ (∼3.8 times higher than that of its counterpart made from pure ZnO QDs) and 0.049 mA W⁻¹, respectively. This study presents an all-solution approach for the fabrication of photodetectors from plasmonic metal/semiconductor heterostructures.