Anchoring Cs4PbBr6 Crystals to PbSe Nanocrystals for the Fabrication of UV/VIS/NIR Photodetectors Using Halide Surface Chemistry

Nanocrystal (NC)‐in‐matrix solids are currently attracting considerable research attention in the fields of materials science and engineering owing to their unique optoelectronic characteristics and high stability. However, the interaction between the NC surface and the matrix has been veiled and induces interface defect states that degrade the performance of photovoltaics. In this study, the effect of halide ligands on the formation of a Cs4PbBr6 (CPB) crystal matrix by determining the surfaces of PbSe NCs is investigated. The surface of the PbSe NCs is passivated with halide ions (Cl−, Br−, or I−), and the CPB crystal matrix is formed via PbBr2/CsBr treatment onto the PbSe NCs. The effects of different halide ions on the nucleation/growth of the CPB matrix are examined by chemical, structural, and optical analyses. It is found that each halide ligand has a distinct effect not only on the anchoring of CPB but also on its carrier transport mechanisms. To characterize the electronic properties of the NC matrix, its carrier mobility, photoresponsivity, and stability are measured using field‐effect transistors. Consequently, it is demonstrated that more densely passivated PbSe NCs form a higher‐quality CPB matrix. Using a NC matrix, ultraviolet‐/visible‐/near‐infrared‐active flexible photodetectors are achieved. The effects of halide treatment on the anchoring of Cs4PbBr6 crystals onto PbSe nanocrystal thin films are investigated. The structural, optical, and electronic properties of the films, as well as their device performance, demonstrate that the halide is critical for perovskite nucleation, growth, and charge transport in the matrix. A PbSe/Cs4PbBr6 core/matrix‐structure‐based thin‐film transistor and UV/VIS/NIR photodetectors are fabricated using Cl− inorganic interfacial ligands.