Substrate mediated broadband photoresponse from MoS2-UCNP/Graphene hybrid photodetectors

Digvijay Singh Tomar^1*, Sandip Ghosh¹, Chien Ting Wu², Shaham Quadir^3,4, Li Chyong Chen⁴, Kuei Hsien Chen^3,4, Surojit Chattopadhyay¹

¹Institute of Biophotonics, National Yang Ming Chiao Tung University, 155, Sec-2 Linong Street, Taipei 112, Taiwan
²National Applied Research Laboratories, Taiwan Semiconductor Research Institute, Hsinchu, Taiwan
³Institute of Atomic & Molecular Sciences, Academia Sinica, 1 Roosevelt Road, Sec-4, Taipei 106, Taiwan
⁴Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Road, Sec-4, Taipei 106, Taiwan

* Presenter:Digvijay Singh Tomar, email:dyrllr@gmail.com

Molybdenum disulfide (MoS2), and upconversion nanoparticles (UCNPs) were loaded on to monolayer CVD graphene (G) coated polydimethylsiloxane (PDMS), and silica/silicon (SiO2/Si) substrates for broadband photoresponse in hybrid photodetector (PD) devices. UCNPs broaden the bandgap-limited response of pure MoS2 , available upto ~680 nm, by absorbing in the infrared (980 nm). Graphene assisted in the charge transport. Identically fabricated PDs on PDMS and SiO2/Si showed the highest photoresponsivity (R) of 26.18, and 84.52 A W-1, respectively, under 1 mW/cm2 of 661 nm laser illumination at 1 V bias. The SiO2/Si substrate-based PDs showed a faster response (~100 ms) compared to the flexible PDMS based PD (~3 s). The PDMS based PD showed a reasonably stable photocurrent, decaying by ~39 %, under 250 repetitive cycles of 6.25 % bending strain; a maximum decrease of ~40 % of the photocurrent was observed under 11.11 % bending strain compared to the as-prepared flat PD. These devices can detect signals from household appliances like air conditioner remotes, laser pointers, and cellphone flashlights.

Keywords: MoS2, Graphene, Upconversion nanoparticle, Photodetector, Flexible