High-Responsivity PEDOT:PSS/SnS<sub>2</sub>/MoS<sub>2</sub> Double-Heterostructure-Based Organic–Inorganic Broadband Photodetector
Ajay Kumar Dwivedi, Satyabrata Jit, Shweta Tripathi
Abstract
This current article proposes an Al/tin disulfide (SnS2)/molybdenum disulfide (MoS2)/poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS)/indium tin oxide (ITO) structure-based organic–inorganic broadband photodetector fabricated on an ITO-coated PET (ductile polyethylene terephthalate) substrate using low-cost sol–gel method. The PEDOT:PSS acts as the active material cum hole transport layer (HTL), while the SnS2 acts as the active material cum electron transport layer (ETL) in the device. The large band offset between MoS2 and SnS2 creates an efficient built-in electric field at the depletion region of MoS2/SnS2 heterojunction, which enhances the drifting of photogenerated carriers to improve the photocurrent of the proposed photodetector. At −1-V bias and 0.118- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{W}$ </tex-math></inline-formula> illumination, the proposed device showed a broad photoresponse with the maximum responsivity, detectivity, external quantum efficiency (EQE), and sensitivity of 548.26 A/W, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.49\times 10^{{12}}$ </tex-math></inline-formula> Jones, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.94\times 10^{{5}}$ </tex-math></inline-formula> %, and 5.44 at 350 nm; 1389.08 A/W, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$6.31\times 10^{{12}}$ </tex-math></inline-formula> Jones, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.82\times 10^{{5}}$ </tex-math></inline-formula> %, and 13.80 at 450 nm; and 457.47 A/W, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.07\times 10^{{12}}$ </tex-math></inline-formula> Jones, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.72\times 10^{{4}}$ </tex-math></inline-formula> %, and 4.54 at 1150 nm, respectively. The rise time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$67.10~\mu \text{s}$ </tex-math></inline-formula> and recovery time of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$80.27~\mu \text{s}$ </tex-math></inline-formula> were obtained at 450-nm wavelength. The high responsivity and EQE beyond 100% are attributed to the trap-assisted photomultiplication (PM) phenomena due to defects in SnS2 of the active layer.