Hybrid Nanostructures of 2D CdSe Nanoplatelets for High-Performance Photodetector Using Charge Transfer Process

Two-dimensional (2D) semiconductor colloidal nanoplatelets (NPLs) have shown great potential as light-harvesting materials due to their advanced optical properties. Here, we designed hybrid nanostructures of 2D CdSe nanoplatelets with phenothiazine (PTZ) for high-performance photodetector with varying thickness of CdSe NPLs by controlling the charge transfer process. Significant photoluminescence quenching and the shortening of the average decay time of CdSe NPLs in the presence of PTZ reveal the charge transfer process. Transient absorption spectroscopic analysis reveals the hot carrier cooling dynamics varies with changing the thickness of monolayers (ML) of CdSe NPLs. Furthermore, the slow exciton recombination of CdSe NPLs in the presence of PTZ indicates the efficient charge separation. The optimized CdSe NPLs-PTZ hybrid exhibits a significant enhancement of photocurrent (∼(4.7 × 103)-fold photo-to-dark current ratio) as compared to pure 3 ML CdSe NPLs (∼10 fold) at the applied voltage of 1.5 V. The measured external quantum efficiency, maximum detectivity, and response time for the optimized hybrid are found to be ∼40%, 4 × 1011 Jones, and 107 ms, with the responsivity value of 160 mA/W. These highly efficient measured parameters clearly suggest that CdSe NPLs-PTZ hybrid systems are a promising alternate for ultrasensitive photodetector.