Hybrid 2D-QD MoS2–PbSe quantum dot broadband photodetectors with high-sensitivity and room-temperature operation at 2.5 µm

Abstract

Broadband infrared photodetectors have profound importance in diverse applications including security, gas sensing, bioimaging, spectroscopy for food quality, and recycling, just to name a few. Yet, these applications can currently be served by expensive epitaxially grown photodetectors, limiting their market potential and social impact. The use of colloidal quantum dots (CQDs) and 2D materials in a hybrid layout is an attractive alternative to design low-cost complementary metal-oxide-semiconductor (CMOS) compatible infrared photodetectors. However, the spectral sensitivity of these conventional hybrid detectors is restricted to 2.1 µm. Herein, a hybrid structure comprising molybdenum disulfide (MoS2) with lead selenide (PbSe) CQDs is presented to extend their sensitivity further toward the mid-wave infrared, up to 3 µm. A room-temperature responsivity of 137.6 A/W and a detectivity of 7.7 × 10^10 Jones are achieved at 2.55 µm owing to highly efficient photoexcited carrier separation at the interface of MoS2 and PbSe in combination with an oxide coating to reduce dark current; the highest value is yet for a PbSe-based hybrid device. These findings strongly support the successful fabrication of hybrid devices, which may pave the pathway for cost-effective, high-performance, next-generation, novel photodetectors. ; The authors acknowledge financial support from the European Research Council (ERC) under the European Union's Horizon 2020 research (grant agreement no. 725165) as well as Graphene Flagship under Grant Agreement Nr. 881603 (Core3). The authors also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO), and the "Fondo Europeo de Desarrollo Regional" (FEDER) through grant TEC2017-88655-R, from the Spanish State Research Agency through the "Severo Ochoa" program for Centers of Excellence in R&D (CEX2019-000910-S), from Fundació Cellex, Fundació Mir-Puig, and from Generalitat de Catalunya through the CERCA program. ; Peer Reviewed ; Postprint (author's final draft)