Advanced PbS quantum dot superlattices for high-performance electrical transport and infrared photodetection integrated with two-dimensional MoS2

The optoelectronics field has recently experienced a notable surge in research studies focused on hybrid structures that integrate colloidal quantum dots (QDs) with two-dimensional (2D) materials. However, photodetectors based on QDs are frequently constrained by charge transport within the QD films, primarily due to the presence of high-energy states and spatial disorder within the QDs, which arise from conventional fabrication methods. To mitigate this issue, this study introduces an innovative method to overcome this limitation by successfully growing and transferring micrometer-scale mesocrystalline, oriented packed p-type triangular PbS QD superlattices (SLs) onto n-type multilayered MoS2. Compared to pristine MoS2, the PbS QD SLs/MoS2 photodetector exhibits an enhanced current on-off ratio of 1.6 x 107 and electron mobility of 10.5 cm2 V-1 s-1, attributed to type-I band alignment with efficient electron injection into the MoS2 channel by depleting the remaining holes. The miniband characteristics within PbS QD SLs endowed effective coupling within the mesocrystals, leading to an effective charge transfer process and prolonging the carrier lifetime, culminating in remarkable photogating performance in shortwave infrared (SWIR) (808-1550 nm) photodetection for the MoS2 channel, a boosted high responsivity of up to 738 A W-1, a high specific detectivity of 5.08 x 1010 Jones, and a gain of 59 201% at a wavelength of 1550 nm with the hole accumulation at the PbS side and Vgs = 60 V. This study thoroughly examines the interfacial mechanisms between QD SLs and MoS2, demonstrating the potential applications of next-generation QD SLs/2D hybrid SWIR photodetectors.