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

Abstract

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 × 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 × 10¹⁰ Jones, and a gain of 59 201% at a wavelength of 1550 nm with the hole accumulation at the PbS side and V_gs = 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.