High Sensitivity Hybrid PbS CQD-TMDC Photodetectors up to 2 μm

Recent approaches to develop infrared photodetectors characterized by high sensitivities, broadband spectral coverage, easy integration with silicon electronics, and low cost have been based on hybrid structures of transition metal dichalcogenides (TMDCs) and PbS colloidal quantum dots (CQDs). However, to date, such photodetectors have been reported with high sensitivity up to 1.5 μm. Here we extend the spectral coverage of this technology toward 2 μm, demonstrating for the first time compelling performance with responsivities 1400 A/W at 1.8 μm with 1 V bias and detectivities as high as 1012 Jones at room temperature. To do this, we studied two TMDC materials as a carrier transport layer, tungsten disulfide (WS2), and molybdenum disulfide (MoS2) and demonstrate that WS2-based hybrid photodetectors outperform those of MoS2 due to a more adequate band alignment that favors carrier transfer from the CQDs.